Organometallic compound, organic light-emitting device including the organometallic compound, and diagnostic composition including the organometallic compound

ABSTRACT

An organometallic compound represented by Formula 1: 
     
       
         
         
             
             
         
       
         
         
           
             wherein, in Formula 1, groups and variables are the same as described in the specification.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No. 10-2017-0029058, filed on Mar. 7, 2017, and Korean Patent Application No. 10-2018-0026193, file on Mar. 6, 2018, in the Korean Intellectual Property Office, and all the benefits accruing therefrom under 35 U.S.C. 119, the content of which is incorporated herein in its entirety by reference.

BACKGROUND 1. Field

One or more embodiments relate to an organometallic compound, an organic light-emitting device including the organometallic compound, and a diagnostic composition including the organometallic compound.

2. Description of the Related Art

Organic light-emitting devices (OLEDs) are self-emission devices, which have superior characteristics in terms of a viewing angle, a response time, a brightness, a driving voltage, and a response speed, and produce full-color images.

A typical organic light-emitting device includes an anode, a cathode, and an organic layer disposed between the anode and the cathode, wherein the organic layer includes an emission layer. A hole transport region may be disposed between the anode and the emission layer, and an electron transport region may be disposed between the emission layer and the cathode. Holes provided from the anode may move toward the emission layer through the hole transport region, and electrons provided from the cathode may move toward the emission layer through the electron transport region. The holes and the electrons recombine in the emission layer to produce excitons. These excitons transit from an excited state to a ground state, thereby generating light.

Meanwhile, luminescent compounds may be used to monitor, sense, or detect a variety of biological materials including cells and proteins. An example of the luminescent compounds includes a phosphorescent luminescent compound.

Various types of organic light emitting devices are known. However, there still remains a need in OLEDs having low driving voltage, high efficiency, high brightness, and long lifespan.

SUMMARY

One or more embodiments include a novel organometallic compound, an organic light-emitting device including the organometallic compound, and a diagnostic composition including the organometallic compound.

Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments.

According to one or more embodiments, an organometallic compound is represented by Formula 1:

In Formula 1,

-   -   M may be a first-row transition metal of the Periodic Table of         Elements, a second-row transition metal of the Periodic Table of         Elements, or a third-row transition metal of the Periodic Table         of Elements,     -   X₁ may be N,     -   X₂ to X₄ may each independently be C or N,     -   two bonds selected from a bond between X₁ and M, a bond between         X₂ and M, a bond between X₃ and M, and a bond between X₄ and M         may each be a coordinate bond, and the others thereof may each         be a covalent bond,     -   Y₁ to Y₆ may each independently be C or N,     -   Y₇ and Y₈ may each independently be C, N, O, Si, or S,     -   X₁ and Y₇, X₁ and Y₁, X₂ and Y₂, X₂ and Y₃, X₃ and Y₄, X₃ and         Y₅, X₄ and Y₆, and X₄ and Y₈ may each be linked via a chemical         bond,     -   CY₁ may be a C₁-C₃₀ heterocyclic group,     -   CY₂ to CY₄ may each independently be a C₅-C₃₀ carbocyclic group         or a C₁-C₃₀ heterocyclic group,     -   T₁ to T₃ may each independently be selected from         *—N[(L₅)_(b5)-(R₅)]—*′, *—B(R₅)—*′, *—P(R₅)—*′, *—C(R₅)(R₆)—*′,         *—Si(R₅)(R₆)—*′, *—Ge(R₅)(R₆)—*′, *—S—*′, *—Se—*′, *—O—*′,         *—C(═O)—*′, *—S(═O)—*′, *—S(═O)₂—*′, *—C(R₅)═, *═C(R₅)—*′,         *—C(R₅)═C(R₆)—*′, *—C(═S)—*′, and *—C≡C—*′,     -   L₅ may be selected from a single bond, a substituted or         unsubstituted C₅-C₃₀ carbocyclic group, and a substituted or         unsubstituted C₁-C₃₀ heterocyclic group,     -   b5 may be selected from 1 to 3, wherein, when b5 is two or more,         two or more groups L₅ may be identical to or different from each         other,     -   R₅ and R₆ may optionally be linked via a first linking group to         form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or         a substituted or unsubstituted C₁-C₃₀ heterocyclic group,     -   n1 to n3 may each independently be 0, 1, 2, or 3, wherein, when         n1 is zero, *-(T₁)_(n1)—*′ may be a single bond, when n2 is         zero, *-(T₂)_(n2)—*′ may be a single bond, and when n3 is zero,         *-(T₃)_(n3)—*′ may be a single bond,     -   R₇₁ in Formula 1 may be a group represented by Formula 71,         *-(L₇₁)_(b71)-(T₇₁)_(c71)  Formula 71     -   wherein, in Formula 71,     -   L₇₁ may be selected from:     -   a C₂-C₆₀ alkylene group; and     -   a C₂-C₆₀ alkylene group substituted with at least one selected         from deuterium, a deuterated C₁-C₆₀ alkyl group, a C₃-C₁₀         cycloalkyl group, and a C₃-C₁₀ cycloalkenyl group,     -   b71 may be 0, 1, or 2,     -   T₇₁ may be selected from:     -   a C₁-C₆₀ alkyl group; and     -   a C₁-C₆₀ alkyl group substituted with at least one selected from         deuterium, a deuterated C₁-C₆₀ alkyl group, a C₃-C₁₀ cycloalkyl         group, and a C₃-C₁₀ cycloalkenyl group,     -   c71 may be an integer from 1 to 10,     -   R₇₂ in Formula 1 may be a group represented by Formula 72,         *-(L₇₂)_(b72)-(T₇₂)_(c72),  Formula 72     -   wherein, in Formula 72,     -   L₇₂ may be selected from:     -   a C₆-C₆₀ arylene group, a C₁-C₆₀ heteroarylene group, a divalent         non-aromatic condensed polycyclic group, and a divalent         non-aromatic condensed heteropolycyclic group; and     -   a C₆-C₆₀ arylene group, a C₁-C₆₀ heteroarylene group, a divalent         non-aromatic condensed polycyclic group, and a divalent         non-aromatic condensed heteropolycyclic group, each substituted         with at least one selected from deuterium, a C₁-C₆₀ alkyl group,         a deuterated C₁-C₆₀ alkyl group, a C₃-C₁₀ cycloalkyl group, a         C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a         C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₁-C₆₀         heteroaryl group, a monovalent non-aromatic condensed polycyclic         group, and a monovalent non-aromatic condensed heteropolycyclic         group,     -   b72 may be 0, 1, or 2,     -   T₇₂ may be selected from:     -   a C₆-C₆₀ aryl group, a C₁-C₆₀ heteroaryl group, a monovalent         non-aromatic condensed polycyclic group, and a monovalent         non-aromatic condensed heteropolycyclic group; and     -   a C₆-C₆₀ aryl group, a C₁-C₆₀ heteroaryl group, a monovalent         non-aromatic condensed polycyclic group, and a monovalent         non-aromatic condensed heteropolycyclic group, each substituted         with at least one selected from deuterium, a C₁-C₆₀ alkyl group,         a deuterated C₁-C₆₀ alkyl group, a C₃-C₁₀ cycloalkyl group, a         C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a         C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₁-C₆₀         heteroaryl group, a monovalent non-aromatic condensed polycyclic         group, and a monovalent non-aromatic condensed heteropolycyclic         group,     -   c72 may be an integer from 1 to 10,     -   wherein, in Formula 1,     -   a71 and a72 may each independently be an integer from 1 to 5,     -   R₁ to R₆ may each independently be selected from hydrogen,         deuterium, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a substituted or unsubstituted C₁-C₆₀ alkyl group, a         substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted         or unsubstituted C₂-C₆₀ alkynyl group, a substituted or         unsubstituted C₁-C₆₀ alkoxy group, a substituted or         unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or         unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or         unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted         C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀         arylthio group, a substituted or unsubstituted C₇-C₆₀ arylalkyl         group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a         substituted or unsubstituted C₁-C₆₀ heteroaryloxy group, a         substituted or unsubstituted C₁-C₆₀ heteroarylthio group, a         substituted or unsubstituted C₂-C₆₀ heteroarylalkyl group, a         substituted or unsubstituted monovalent non-aromatic condensed         polycyclic group, a substituted or unsubstituted monovalent         non-aromatic condensed heteropolycyclic group, —N(Q₁)(Q₂),         —Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉),     -   a1 to a4 may each independently be 0, 1, 2, 3, 4, or 5,     -   Formula 1 does not include fluorine (—F),     -   two of groups R₁ in the number of a1 may optionally be linked to         form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or         a substituted or unsubstituted C₁-C₃₀ heterocyclic group,     -   two of groups R₂ in the number of a2 may optionally be linked to         form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or         a substituted or unsubstituted C₁-C₃₀ heterocyclic group,     -   two of groups R₃ in the number of a3 may optionally be linked to         form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or         a substituted or unsubstituted C₁-C₃₀ heterocyclic group,     -   two of groups R₄ in the number of a4 may optionally be linked to         form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or         a substituted or unsubstituted C₁-C₃₀ heterocyclic group,     -   two or more neighboring groups selected from R₁ to R₄ may         optionally be linked to form a substituted or unsubstituted         C₅-C₃₀ carbocyclic group or a substituted or unsubstituted         C₁-C₃₀ heterocyclic group,     -   one of R₅ and R₆ and one of R₁ to R₄ may optionally be linked to         form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or         a substituted or unsubstituted C₁-C₃₀ heterocyclic group,     -   at least one substituent of the substituted C₅-C₃₀ carbocyclic         group, the substituted C₁-C₃₀ heterocyclic group, the         substituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀ alkenyl         group, the substituted C₂-C₆₀ alkynyl group, the substituted         C₁-C₆₀ alkoxy group, the substituted C₃-C₁₀ cycloalkyl group,         the substituted C₁-C₁₀ heterocycloalkyl group, the substituted         C₃-C₁₀ cycloalkenyl group, the substituted C₁-C₁₀         heterocycloalkenyl group, the substituted C₆-C₆₀ aryl group, the         substituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀         arylthio group, the substituted C₇-C₆₀ arylalkyl group, the         substituted C₁-C₆₀ heteroaryl group, the substituted C₁-C₆₀         heteroaryloxy group, the substituted C₁-C₆₀ heteroarylthio         group, the substituted C₂-C₆₀ heteroarylalkyl group, the         substituted monovalent non-aromatic condensed polycyclic group,         and the substituted monovalent non-aromatic condensed         heteropolycyclic group may be selected from:     -   deuterium, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, a hydroxyl group, a         cyano group, a nitro group, an amidino group, a hydrazine group,         a hydrazone group, a carboxylic acid group or a salt thereof, a         sulfonic acid group or a salt thereof, a phosphoric acid group         or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group,         a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy group;     -   a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl         group, and a C₁-C₆₀ alkoxy group, each substituted with at least         one selected from deuterium, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, a         hydroxyl group, a cyano group, a nitro group, an amidino group,         a hydrazine group, a hydrazone group, a carboxylic acid group or         a salt thereof, a sulfonic acid group or a salt thereof, a         phosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl         group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl         group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a         C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀         arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀         heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a C₂-C₆₀         heteroarylalkyl group, a monovalent non-aromatic condensed         polycyclic group, a monovalent non-aromatic condensed         heteropolycyclic group, —N(Q₁₁)(Q₁₂), —Si(Q₁₃)(Q₁₄)(Q₁₅),         —B(Q₁₆)(Q₁₇), and —P(═O)(Q₁₈)(Q₁₉);     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a         C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a         C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic         condensed polycyclic group, and a monovalent non-aromatic         condensed heteropolycyclic group;     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a         C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a         C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic         condensed polycyclic group, and a monovalent non-aromatic         condensed heteropolycyclic group, each substituted with at least         one selected from deuterium, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, a         hydroxyl group, a cyano group, a nitro group, an amidino group,         a hydrazine group, a hydrazone group, a carboxylic acid group or         a salt thereof, a sulfonic acid group or a salt thereof, a         phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a         C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy         group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl         group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl         group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀         arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl         group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio         group, a C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic         condensed polycyclic group, a monovalent non-aromatic condensed         heteropolycyclic group, —N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅),         —B(Q₂₆)(Q₂₇), and —P(═O)(Q₂₈)(Q₂₉); and     -   —N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅), —B(Q₃₆)(Q₃₇), and         —P(═O)(Q₃₈)(Q₃₉), and     -   Q₁ to Q₉, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, and Q₃₁ to Q₃₉ may each         independently be selected from hydrogen, deuterium, —Cl, —Br,         —I, a hydroxyl group, a cyano group, a nitro group, an amidino         group, a hydrazine group, a hydrazone group, a carboxylic acid         group or a salt thereof, a sulfonic acid group or a salt         thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀         alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a         C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀         heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀         heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryl         group substituted with at least one selected from a C₁-C₆₀ alkyl         group and a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀         arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl         group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio         group, a C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic         condensed polycyclic group, and a monovalent non-aromatic         condensed heteropolycyclic group.

According to one or more embodiments, an organic light-emitting device includes:

-   -   a first electrode;     -   a second electrode; and     -   an organic layer that is disposed between the first electrode         and the second electrode,     -   wherein the organic layer includes an emission layer and at         least one of the organometallic compound.

The organometallic compound may act as a dopant in the organic layer.

According to one or more embodiments, a diagnostic composition includes at least one of the organometallic compound represented by Formula 1.

BRIEF DESCRIPTION OF THE DRAWING

These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the FIGURE which is a schematic view of an organic light-emitting device according to an embodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the FIGURES, to explain aspects of the present description. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.

It will be understood that when an element is referred to as being “on” another element, it can be directly in contact with the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.

It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section.

Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of the present embodiments.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

The term “or” means “and/or.” It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this general inventive concept belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to cross section illustrations that are schematic illustrations of idealized embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the present claims.

“About” or “approximately” as used herein is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “about” can mean within one or more standard deviations, or within ±30%, 20%, 10%, 5% of the stated value.

In an embodiment, an organometallic compound is provided. The organometallic compound according to an embodiment may be represented by Formula 1 below:

M in Formula 1 may be a first-row transition metal of the Periodic Table of Elements, a second-row transition metal of the Periodic Table of Elements, and a third-row transition metal of the Periodic Table of Elements.

For example, M in Formula 1 may be platinum (Pt) or palladium (Pd), but embodiments of the present disclosure are not limited thereto.

The organometallic compound represented by Formula 1 may be a neutral compound that does not consist of an ion pair of an anion and a cation.

In Formula 1, X₁ may be N, and X₂ to X₄ may each independently be C or N.

In Formula 1, two bonds selected from a bond between X₁ and M, a bond between X₂ and M, a bond between X₃ and M, and a bond between X₄ and M may each be a coordinate bond, and the others thereof may each be a covalent bond.

In an embodiment, in Formula 1, X₂ and X₃ may each be carbon, X₄ may be nitrogen, a bond between X₂ and M and a bond between X₃ and M may each be a covalent bond, and a bond between X₁ and M and a bond between X₄ and M may each be a coordinate bond, but embodiments of the present disclosure are not limited thereto.

In Formula 1, Y₁ to Y₆ may each independently be C or N, and Y₇ and Y₈ may each independently be C, N, O, Si, or S.

In an embodiment, in Formula 1, Y₁ to Y₅ may each be C, and Y₆ to Y₈ may each independently be C or N, but embodiments of the present disclosure are not limited thereto.

X₁ and Y₇, X₁ and Y₁, X₂ and Y₂, X₂ and Y₃, X₃ and Y₄, X₃ and Y₅, X₄ and Y₆, and X₄ and Y₈ in Formula 1 may each be linked via a chemical bond.

In Formula 1, CY₁ may be a C₁-C₃₀ heterocyclic group, and CY₂ to CY₄ may each independently be a C₅-C₃₀ carbocyclic group or a C₁-C₃₀ heterocyclic group.

For example, in Formula 1, CY₁ may be selected from a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrrole group, a pyrazole group, an imidazole group, a triazole group, a tetrazole group, an oxazole group, an isoxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, a benzothiadiazole group, a 5,6,7,8-tetrahydroisoquinoline group, and a 5,6,7,8-tetrahydroquinoline group, and CY₂ to CY₄ may each independently be selected from a benzene group, a naphthalene group, an anthracene group, a phenanthrene group, a triphenylene group, a pyrene group, a chrysene group, a cyclopentadiene group, a 1,2,3,4-tetrahydronaphthalene group, a pyrrole group, a thiophene group, a furan group, an indole group, a benzoborol group, a benzophosphole group, an indene group, a benzosilole group, a benzogermole group, a benzothiophene group, a benzoselenophene group, a benzofuran group, a carbazole group, a dibenzoborole group, a dibenzophosphole group, a fluorene group, a dibenzosilole group, a dibenzogermole group, a dibenzothiophene group, a dibenzoselenophene group, a dibenzofuran group, a dibenzothiophene 5-oxide group, a 9H-fluorene-9-on group, a dibenzothiophene 5,5-dioxide group, an azacarbazole group, an azadibenzoborole group, an azadibenzophosphole group, an azafluorene group, an azadibenzosilole group, an azadibenzogermole group, an azadibenzothiophene group, an azadibenzoselenophene group, an azadibenzofuran group, an azadibenzothiophene 5-oxide group, an aza-9H-fluorene-9-on group, an azadibenzothiophene 5,5-dioxide group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrazole group, an imidazole group, a triazole group, a tetrazole group, an oxazole group, an isoxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, a benzothiadiazole group, a 5,6,7,8-tetrahydroisoquinoline group, and a 5,6,7,8-tetrahydroquinoline group.

In an embodiment, in Formula 1, CY₁ and CY₄ may each independently be selected from a pyridine group, a pyrimidine group, a triazine group, a quinoline group, an isoquinoline group, a quinoxaline group, a quinazoline group, a pyrazole group, an imidazole group, and a triazole group, and CY₂ and CY₃ may each independently be selected from a benzene group, a naphthalene group, a 1,2,3,4-tetrahydronaphthalene group, a carbazole group, a fluorene group, a dibenzothiophene group, and a dibenzofuran group, but embodiments of the present disclosure are not limited thereto.

“An azacarbazole group, an azadibenzoborole group, an azadibenzophosphole group, an azafluorene group, an azadibenzosilole group, an azadibenzogermole group, an azadibenzothiophene group, an azadibenzoselenophene group, an azadibenzofuran group, an azadibenzothiophene 5-oxide group, an aza-9H-fluorene-9-on group, and an azadibenzothiophene 5,5-dioxide group” as used herein mean hetero-rings that respectively have the same backbones as “a carbazole group, a dibenzoborole group, a dibenzophosphole group, a fluorene group, a dibenzosilole group, a dibenzogermole group, a dibenzothiophene group, a dibenzoselenophene group, a dibenzofuran group, a dibenzothiophene 5-oxide group, a 9H-fluorene-9-on group, and a dibenzothiophene 5,5-dioxide group”, provided that at least one of carbons forming rings thereof is substituted with nitrogen.

CY₁ and CY₄ in Formula 1 may be identical to each other, but embodiments of the present disclosure are not limited thereto.

In an embodiment, CY₂ and CY₃ in Formula 1 may be identical to each other, but embodiments of the present disclosure are not limited thereto.

In an embodiment, in Formula 1, a moiety represented by

and a moiety represented by

may be identical to each other, and a moiety represented by

and a moiety represented by

may be identical to each other.

In one or more embodiments, the organometallic compound may have a symmetrical structure with respect to an axis connecting M and T₁ in Formula 1.

T₁ to T₃ in Formula 1 may each independently be selected from *—N[(L₅)_(b5)-(R₅)]—*′, *—B(R₅)—*′, *—P(R₅)—*′, *—C(R₅)(R₆)—*′, *—Si(R₅)(R₆)—*′, *—Ge(R₅)(R₆)—*′, *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′, *—S(═O)—*′, *—S(═O)₂—*′, *—C(R₅)═*′, *═C(R₅)—*′, *—C(R₅)═C(R₆)—*′, *—C(═S)—*′, and *—C≡C—*′. R₅ and R₆ are each independently the same as described below.

L₅ may be selected from a single bond, a substituted or unsubstituted C₅-C₃₀ carbocyclic group, and a substituted or unsubstituted C₁-C₃₀ heterocyclic group, and b5 may be selected from 1 to 3 (for example, b5 may be 1), wherein, when b5 is two or more, two or more groups L₅ may be identical to or different from each other.

In an embodiment, L₅ may be selected from:

-   -   a single bond, a phenylene group, a naphthylene group, a         fluorenylene group, a pyridinylene group, a pyrimidinylene         group, and a carbazolylene group; and     -   a phenylene group, a naphthylene group, a fluorenylene group, a         pyridinylene group, a pyrimidinylene group, and a carbazolylene         group, each substituted with at least one selected from         deuterium, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, a hydroxyl group, a         cyano group, a nitro group, an amino group, an amidino group, a         hydrazine group, a hydrazone group, a carboxylic acid group or a         salt thereof, a sulfonic acid group or a salt thereof, a         phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a         C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a         biphenyl group, and a terphenyl group,     -   but embodiments of the present disclosure are not limited         thereto.

R₅ and R₆ may optionally be linked via a first linking group to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group (a C₅-C₆ 5-membered to 7-membered cyclic group; or a C₅-C₆ 5-membered to 7-membered cyclic group substituted with at least one selected from deuterium, a cyano group, a C₁-C₁₀ alkyl group, and a C₆-C₁₄ aryl group).

In an embodiment, T₁ to T₃ in Formula 1 may each independently be selected from *—N[(L₅)_(b5)-(R₅)]—*′, *—B(R₅)—*′, *—C(R₅)(R₆)—*′, *—Si(R₅)(R₆)—*′, *—S—*′, *—O—*′, and *—C(═O)—*′, but embodiments of the present disclosure are not limited thereto.

In one or more embodiments, T₁ to T₃ in Formula 1 may each independently be selected from *—C(R₅)(R₆)—*′, *—Si(R₅)(R₆)—*′, and *—Ge(R₅)(R₆)—*′,

-   -   R₅ and R₆ may be linked via a first linking group,     -   the first linking group may be selected from a single bond,         *—N[(L₉)_(b9)-(R₉)]—*′, *—B(R₉)—*′, *—P(R₉)—*′, *—C(R₉)(R₁₀)—*′,         *—Si(R₉)(R₁₀)—*′, *—Ge(R₉)(R₁₀)—*′, *—S—*′, *—Se—*′, *—O—*′,         *—C(═O)—*′, *—S(═O)—*′, *—S(═O)₂—*′, *—C(R₉)═C(R₁₀)—*′,         *—C(═S)—*′, and *—C≡C—*′,     -   L₉ and b9 are each independently the same as described in         connection with L₅ and b5,     -   R₉ and R₁₀ are each independently the same as described in         connection with R₅, and     -   * and *′ each indicate a binding site to a neighboring atom, but         embodiments of the present disclosure are not limited thereto.

n1 to n3 in Formula 1 may each independently be 0, 1, 2, or 3, wherein, when n1 is zero, *-(T₁)_(n1)—*′ may be a single bond, when n2 is zero, *-(T₂)_(n2)—*′ may be a single bond, and when n3 is zero, *-(T₃)_(n3)—*′ may be a single bond. When n1 is two or more, two or more groups T₁ may be identical to or different from each other, when n2 is two or more, two or more groups T₂ may be identical to or different from each other, and when n3 is two or more, two or more groups T₃ may be identical to or different from each other.

In an embodiment, n1 to n3 in Formula 1 may each independently be 0 or 1.

In one or more embodiments, the sum of n1, n2, and n3 in Formula 1 may be 0 or 1.

In one or more embodiments, in Formula 1, n1 may be 1, and n2 and n3 may be 0 or 1.

R₇₁ in Formula 1 may be a group represented by Formula 71: *-(L₇₁)_(b71)-(T₇₁)_(c71).  Formula 71

In Formula 71,

-   -   L₇₁ may be selected from:     -   a C₂-C₆₀ alkylene group; and     -   a C₂-C₆₀ alkylene group substituted with at least one selected         from deuterium, a deuterated C₁-C₆₀ alkyl group, a C₃-C₁₀         cycloalkyl group, and a C₃-C₁₀ cycloalkenyl group,     -   b71 may be 0, 1, or 2,     -   T₇₁ may be selected from:     -   a C₁-C₆₀ alkyl group; and     -   a C₁-C₆₀ alkyl group substituted with at least one selected from         deuterium, a deuterated C₁-C₆₀ alkyl group, a C₃-C₁₀ cycloalkyl         group, and a C₃-C₁₀ cycloalkenyl group, and     -   c71 may be an integer from 1 to 10.

For example, in Formula 71,

-   -   L₇₁ may be selected from:     -   a C₂-C₁₀ alkylene group; and     -   a C₂-C₁₀ alkylene group substituted with at least one selected         from deuterium, a deuterated C₁-C₂₀ alkyl group, a cyclopentyl         group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl         group, an adamantanyl group, a norbonanyl group, a norbonenyl         group, a cyclopentenyl group, a cyclohexenyl group, and a         cycloheptenyl group,     -   b71 may be 0 or 1,     -   T₇₁ may be selected from:     -   a C₁-C₁₀ alkyl group; and     -   a C₁-C₁ alkyl group substituted with at least one selected from         deuterium, a deuterated C₁-C₂₀ alkyl group, a cyclopentyl group,         a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an         adamantanyl group, a norbonanyl group, a norbonenyl group, a         cyclopentenyl group, a cyclohexenyl group, and a cycloheptenyl         group, and     -   c71 may be 1 or 2, but embodiments of the present disclosure are         not limited thereto.

R₇₂ in Formula 1 may be a group represented by Formula 72: *-(L₇₂)_(b72)-(T₇₂)_(c72).  Formula 72

In Formula 72,

-   -   L₇₂ may be selected from:     -   a C₆-C₆₀ arylene group, a C₁-C₆₀ heteroarylene group, a divalent         non-aromatic condensed polycyclic group, and a divalent         non-aromatic condensed heteropolycyclic group; and     -   a C₆-C₆₀ arylene group, a C₁-C₆₀ heteroarylene group, a divalent         non-aromatic condensed polycyclic group, and a divalent         non-aromatic condensed heteropolycyclic group, each substituted         with at least one selected from deuterium, a C₁-C₆₀ alkyl group,         a deuterated C₁-C₆₀ alkyl group, a C₃-C₁₀ cycloalkyl group, a         C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a         C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₁-C₆₀         heteroaryl group, a monovalent non-aromatic condensed polycyclic         group, and a monovalent non-aromatic condensed heteropolycyclic         group,     -   b72 may be 0, 1, or 2,     -   T₇₂ may be selected from:     -   a C₆-C₆₀ aryl group, a C₁-C₆₀ heteroaryl group, a monovalent         non-aromatic condensed polycyclic group, and a monovalent         non-aromatic condensed heteropolycyclic group; and     -   a C₆-C₆₀ aryl group, a C₁-C₆₀ heteroaryl group, a monovalent         non-aromatic condensed polycyclic group, and a monovalent         non-aromatic condensed heteropolycyclic group, each substituted         with at least one selected from deuterium, a C₁-C₆₀ alkyl group,         a deuterated C₁-C₆₀ alkyl group, a C₃-C₁₀ cycloalkyl group, a         C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a         C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₁-C₆₀         heteroaryl group, a monovalent non-aromatic condensed polycyclic         group, and a monovalent non-aromatic condensed heteropolycyclic         group, and     -   c72 may be an integer from 1 to 10.

For example, in Formula 72,

-   -   L₇₂ may be selected from:     -   a phenylene group, a naphthylene group, a pyridinylene group, a         pyrimidinylene group, a triazinylene group, a quinolinylene         group, an isoquinolinylene group, a quinoxalinylene group, a         quinazolinylene group, a fluorenylene group, a carbazolylene         group, a dibenzofuranylene group, and a dibenzothiophenylene         group; and     -   a phenylene group, a naphthylene group, a pyridinylene group, a         pyrimidinylene group, a triazinylene group, a quinolinylene         group, an isoquinolinylene group, a quinoxalinylene group, a         quinazolinylene group, a fluorenylene group, a carbazolylene         group, a dibenzofuranylene group, and a dibenzothiophenylene         group, each substituted with at least one selected from         deuterium, a C₁-C₂₀ alkyl group, a deuterated C₁-C₂₀ alkyl         group, a phenyl group, a naphthyl group, a pyridinyl group, a         pyrimidinyl group, a triazinyl group, a quinolinyl group, an         isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group,         a fluorenyl group, a carbazolyl group, a dibenzofuranyl group,         and a dibenzothiophenyl group,     -   b72 may be 0 or 1,     -   T₇₂ may be selected from:     -   a phenyl group, a naphthyl group, a pyridinyl group, a         pyrimidinyl group, a triazinyl group, a quinolinyl group, an         isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group,         a fluorenyl group, a carbazolyl group, a dibenzofuranyl group,         and a dibenzothiophenyl group; and     -   a phenyl group, a naphthyl group, a pyridinyl group, a         pyrimidinyl group, a triazinyl group, a quinolinyl group, an         isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group,         a fluorenyl group, a carbazolyl group, a dibenzofuranyl group,         and a dibenzothiophenyl group, each substituted with at least         one selected from deuterium, a C₁-C₂₀ alkyl group, a deuterated         C₁-C₂₀ alkyl group, a phenyl group, a naphthyl group, a         pyridinyl group, a pyrimidinyl group, a triazinyl group, a         quinolinyl group, an isoquinolinyl group, a quinoxalinyl group,         a quinazolinyl group, a fluorenyl group, a carbazolyl group, a         dibenzofuranyl group, and a dibenzothiophenyl group, and     -   c72 may be 1 or 2, but embodiments of the present disclosure are         not limited thereto.

a71 and a72 in Formula 1 respectively indicate the number of groups R₇₁ and the number of groups R₇₂, and may each independently be an integer from 1 to 5. That is, CY₁ in Formula 1 is essentially substituted with at least one R₇₁ and at least one R₇₂. a71 and a72 may each independently be 1 or 2. For example, a71 and a72 may each be 1, but embodiments of the present disclosure are not limited thereto.

R₁ to R₆ in Formula 1 may each independently be selected from hydrogen, deuterium, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a substituted or unsubstituted C₇-C₆₀ arylalkyl group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstituted C₁-C₆₀ heteroaryloxy group, a substituted or unsubstituted C₁-C₆₀ heteroarylthio group, a substituted or unsubstituted C₂-C₆₀ heteroarylalkyl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉). Q₁ to Q₀₉ are each independently the same as described herein.

For example, R₁ to R₆ may each independently be selected from:

-   -   hydrogen, deuterium, —Cl, —Br, —I, a hydroxyl group, a cyano         group, a nitro group, an amino group, an amidino group, a         hydrazine group, a hydrazone group, a carboxylic acid group or a         salt thereof, a sulfonic acid group or a salt thereof, a         phosphoric acid group or a salt thereof, C₁-C₂₀ alkyl group, and         a C₁-C₂₀ alkoxy group;     -   a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group, each substituted         with at least one selected from deuterium, —Cl, —Br, —I, —CD₃,         —CD₂H, —CDH₂, a hydroxyl group, a cyano group, a nitro group, an         amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₁₀ alkyl group, a cyclopentyl group, a cyclohexyl         group, a cycloheptyl group, a cyclooctyl group, an adamantanyl         group, a norbornanyl group, a norbornenyl group, a cyclopentenyl         group, a cyclohexenyl group, a cycloheptenyl group, a phenyl         group, a naphthyl group, a pyridinyl group, and a pyrimidinyl         group;     -   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a         cyclooctyl group, an adamantanyl group, a norbornanyl group, a         norbornenyl group, a cyclopentenyl group, a cyclohexenyl group,         a cycloheptenyl group, a phenyl group, a naphthyl group, a         fluorenyl group, a phenanthrenyl group, an anthracenyl group, a         fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a         chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl         group, an imidazolyl group, a pyrazolyl group, a thiazolyl         group, an isothiazolyl group, an oxazolyl group, an isoxazolyl         group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl         group, a pyridazinyl group, an isoindolyl group, an indolyl         group, an indazolyl group, a purinyl group, a quinolinyl group,         an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl         group, a quinazolinyl group, a cinnolinyl group, a carbazolyl         group, a phenanthrolinyl group, a benzimidazolyl group, a         benzofuranyl group, a benzothiophenyl group, an         isobenzothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an         oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a         dibenzothiophenyl group, a benzocarbazolyl group, a         dibenzocarbazolyl group, an imidazopyridinyl group, and an         imidazopyrimidinyl group;     -   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a         cyclooctyl group, an adamantanyl group, a norbornanyl group, a         norbornenyl group, a cyclopentenyl group, a cyclohexenyl group,         a cycloheptenyl group, a phenyl group, a naphthyl group, a         fluorenyl group, a phenanthrenyl group, an anthracenyl group, a         fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a         chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl         group, an imidazolyl group, a pyrazolyl group, a thiazolyl         group, an isothiazolyl group, an oxazolyl group, an isoxazolyl         group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl         group, a pyridazinyl group, an isoindolyl group, an indolyl         group, an indazolyl group, a purinyl group, a quinolinyl group,         an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl         group, a quinazolinyl group, a cinnolinyl group, a carbazolyl         group, a phenanthrolinyl group, a benzimidazolyl group, a         benzofuranyl group, a benzothiophenyl group, an         isobenzothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an         oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a         dibenzothiophenyl group, a benzocarbazolyl group, a         dibenzocarbazolyl group, an imidazopyridinyl group, and an         imidazopyrimidinyl group, each substituted with at least one         selected from deuterium, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, a         hydroxyl group, a cyano group, a nitro group, an amino group, an         amidino group, a hydrazine group, a hydrazone group, a         carboxylic acid group or a salt thereof, a sulfonic acid group         or a salt thereof, a phosphoric acid group or a salt thereof, a         C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a cyclopentyl group,         a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an         adamantanyl group, a norbornanyl group, a norbornenyl group, a         cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl         group, a phenyl group, a naphthyl group, a fluorenyl group, a         phenanthrenyl group, an anthracenyl group, a fluoranthenyl         group, a triphenylenyl group, a pyrenyl group, a chrysenyl         group, a pyrrolyl group, a thiophenyl group, a furanyl group, an         imidazolyl group, a pyrazolyl group, a thiazolyl group, an         isothiazolyl group, an oxazolyl group, an isoxazolyl group, a         pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, an isoindolyl group, an indolyl group, an         indazolyl group, a purinyl group, a quinolinyl group, an         isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl         group, a quinazolinyl group, a cinnolinyl group, a carbazolyl         group, a phenanthrolinyl group, a benzimidazolyl group, a         benzofuranyl group, a benzothiophenyl group, an         isobenzothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an         oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a         dibenzothiophenyl group, a benzocarbazolyl group, a         dibenzocarbazolyl group, an imidazopyridinyl group, an         imidazopyrimidinyl group, —N(Q₃₁)(Q₃₂), and —Si(Q₃₃)(Q₃₄)(Q₃₅);         and     -   —N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉), and     -   Q₁ to Q₉ and Q₃₁ to Q₃₅ may each independently be selected from:     -   —CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂,         —CHDCH₃, —CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and         —CD₂CDH₂;     -   an n-propyl group, an isopropyl group, an n-butyl group, an         isobutyl group, a sec-butyl group, a tert-butyl group, an         n-pentyl group, an isopentyl group, a sec-pentyl group, a         tert-pentyl group, a phenyl group, and a naphthyl group; and     -   an n-propyl group, an iso-propyl group, an n-butyl group, an         isobutyl group, a sec-butyl group, a tert-butyl group, an         n-pentyl group, an isopentyl group, a sec-pentyl group, a         tert-pentyl group, a phenyl group, and a naphthyl group, each         substituted with at least one selected from deuterium, a C₁-C₁₀         alkyl group, and a phenyl group.

In one or more embodiments, in Formula 1,

-   -   R₁ to R₆ may each independently be selected from hydrogen,         deuterium, a cyano group, a nitro group, —CH₃, —CD₃, —CD₂H,         —CDH₂, —OCH₃, groups represented by Formulae 9-1 to 9-19, groups         represented by Formulae 10-1 to 10-168, —N(Q₁)(Q₂), and         —Si(Q₃)(Q₄)(Q₅),     -   R₇₁ may be selected from —CH₃, —CD₃, —CD₂H, —CDH₂, groups         represented by Formulae 9-1 to 9-19, and groups represented by         Formulae 10-5 to 10-8, 10-11, and 10-12, and     -   R₇₂ may be selected from groups represented by Formulae 10-13 to         10-152 and 10-159 to 10-168, but embodiments of the present         disclosure are not limited thereto:

In Formulae 9-1 to 9-19 and 10-1 to 10-168, * indicates a binding site to a neighboring atom, “Ph” indicates a phenyl group, “Cz” indicates a carbazolyl group, and “TMS” indicates a trimethylsilyl group.

a1, a2, a3, and a4 in Formula 1 respectively indicate the number of groups R₁, the number of groups R₂, the number of groups R₁, and the number of groups R₄, and may each independently be 0, 1, 2, 3, 4, or 5. When a1 is two or more, two or more groups R₁ may be identical to or different from each other, when a2 is two or more, two or more groups R₂ may be identical to or different from each other, when a3 is two or more, two or more groups R₃ may be identical to or different from each other, and when a4 is two or more, two or more groups R₄ may be identical to or different from each other, but embodiments of the present disclosure are not limited thereto.

In Formula 1, two of groups R₁ in the number of a1 may optionally be linked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, two of groups R₂ in the number of a2 may optionally be linked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, when two of groups R₃ in the number of a3 may optionally be linked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, two of groups R₄ in the number of a4 may optionally be linked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, two or more neighboring groups selected from R₁ to R₄ may optionally be linked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, and one of R₅ and R₆ and one of R₁ to R₄ may optionally be linked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group.

For example, i) a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, formed by linking two of groups R₁ in the number of a1, ii) a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, formed by two of groups R₂ in the number of a2, iii) a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, formed by linking two of groups R₃ in the number of a3, iv) a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, formed by linking two of groups R₄ in the number of a4, v) a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, formed by linking two neighboring groups selected from R₁ to R₄, and vi) a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, formed by linking one of R₅ and R₆ and one of R₁ to R₄ in Formula 1 may each independently be selected from:

-   -   a pentadiene group, a cyclohexane group, a cyclopentane group,         an adamantane group, a bicycloheptane group, a bicyclo-octane         group, a benzene group, a pyridine group, a pyrimidine group, a         pyrazine group, a pyridazine group, a naphthalene group, an         anthracene group, a tetracene group, a phenanthrene group, a         dihydronaphthalene group, a phenalene group, a benzothiophene         group, a benzofuran group, an indene group, an indole group, a         benzosilole group, an azabenzothiophene group, an azabenzofuran         group, an azaindene group, an azaindole group, and an         azabenzosilole group; and     -   a pentadiene group, a cyclohexane group, a cycloheptane group,         an adamantane group, a bicycloheptane group, a bicyclo-octane         group, a benzene group, a pyridine group, a pyrimidine group, a         pyrazine group, a pyridazine group, a naphthalene group, an         anthracene group, a tetracene group, a phenanthrene group, a         dihydronaphthalene group, a phenalene group, a benzothiophene         group, a benzofuran group, an indene group, an indole group, a         benzosilole group, an azabenzothiophene group, an azabenzofuran         group, an azaindene group, an azaindole group, and an         azabenzosilole group, each substituted with at least one R₁₀,     -   but embodiments of the present disclosure are not limited         thereto.

R₁₀ is the same as described in connection with R₁.

The organometallic compound represented by Formula 1 does not include fluorine (F).

In an embodiment, a moiety represented by

in Formula 1 may be selected from groups represented by Formulae CY1-1 to CY1-6:

In Formulae CY1-1 to CY1-6,

-   -   X₁, R₇₁, R₇₂, and R₁ are each independently the same as         described herein,     -   c2 may be an integer from 0 to 2, and     -   * and *′ each indicate a binding site to a neighboring atom.

In one or more embodiments, a moiety represented by

in Formula 1 may be selected from groups represented by Formulae CY2-1 to CY2-25:

In Formulae CY2-1 to CY2-25,

-   -   X₂ and R₂ are each independently the same as described herein,     -   X₂₁ may be O, S, N(R₂₁), or C(R₂₁)(R₂₂),     -   R₂₁ to R₂₈ are each independently the same as described in         connection with R₂,     -   c5 may be an integer from 0 to 5,     -   c4 may be an integer from 0 to 4,     -   c3 may be an integer from 0 to 3,     -   c2 may be an integer from 0 to 2, and     -   *, *′, and *″ each indicate a binding site to a neighboring         atom.

In one or more embodiments, a moiety represented by

in Formula 1 may be selected from groups represented by Formulae CY3-1 to CY3-25:

In Formulae CY3-1 to CY3-25,

-   -   X₃ and R₃ are each independently the same as described herein,     -   X₃₁ may be O, S, N(R₃₁), or C(R₃₁)(R₃₂),     -   R₃₁ to R₃₈ are each independently the same as described in         connection with R₃,     -   c5 may be an integer from 0 to 5,     -   c4 may be an integer from 0 to 4,     -   c3 may be an integer from 0 to 3,     -   c2 may be an integer from 0 to 2, and     -   *, *′, and *″ each indicate a binding site to a neighboring         atom.

In one or more embodiments, a moiety represented by

in Formula 1 may be selected from groups represented by Formulae CY4-1 to CY4-35:

In Formulae CY4-1 to CY4-35,

-   -   X₄ and R₄ are each independently the same as described herein,     -   X₄₁ may be O, S, N(R₄₁), or C(R₄₁)(R₄₂),     -   R_(71a) is the same as described in connection with R₇₁,     -   R_(72a) is the same as described in connection with R₇₂,     -   R₄₁ to R₄₈ are each independently the same as described in         connection with R₄,     -   c6 may be an integer from 0 to 6,     -   c5 may be an integer from 0 to 5,     -   c4 may be an integer from 0 to 4,     -   c3 may be an integer from 0 to 3,     -   c2 may be an integer from 0 to 2, and     -   * and *′ each indicate a binding site to a neighboring atom.

In one or more embodiments,

-   -   a moiety represented by

in Formula 1 may be selected from groups represented by Formulae CY1(1) and CY1(2), and/or

-   -   a moiety represented by

in Formula 1 may be selected from groups represented by Formulae CY2(1) to CY2(4), and/or

-   -   a moiety represented by

in Formula 1 may be selected from groups represented by Formulae CY3(1) to CY3(4), and/or

-   -   a moiety represented by

in Formula 1 may be selected from groups represented by Formulae CY4(1) to CY4(19), but embodiments of the present disclosure are not limited thereto:

In Formulae CY1(1), CY1(2), CY2(1) to CY2(4), CY3(1) to CY3(4), and CY4(1) to CY4(19),

-   -   X₁, R₁, R₇₁, R₇₂, X₂, R₂, X₃, R₃, X₄, and R₄ are each         independently the same as described herein,     -   X₄₁ may be O, S, N(R₄₁), or C(R₄₁)(R₄₂),     -   R_(4a), R_(4b), R₄₁, and R₄₂ are each independently the same as         described in connection with R₄,     -   R_(71a) is the same as described in connection with R₇₁,     -   R_(72a) is the same as described in connection with R₇₂, and     -   *, *′, and *″ each indicate a binding site to a neighboring         atom.

In one or more embodiments, the organometallic compound may be represented by Formula 1(1):

In Formula 1(1),

-   -   M, X₁ to X₄, Y₁ to Y₈, CY₁ to CY₄, T₂, T₃, b2, b3, R₇₁, R₇₂,         a71, a72, R₁ to R₄, and a1 to a4 are each independently the same         as described herein,     -   CY₅ and CY₆ may each independently be a C₅-C₃₀ carbocyclic group         or a C₁-C₃₀ heterocyclic group,     -   R₅₁ and R₆₁ are each independently the same as described in         connection with R₁,     -   a51 and a61 may each independently be 0, 1, 2, or 3,     -   T₄ may be C, Si, or Ge,     -   T₅ may be selected from a single bond, *—N[(L₇)_(b7)-(R₇)]—*′,         *—C(R₇)(R₈)—*′, *—Si(R₇)(R₈)—*′, *—Ge(R₇)(R₈)—*′, *—S—*′,         *—Se—*′, *—O—*′, *—C(═O)—*′, *—S(═O)—*′, *—S(═O)₂—*′,         *—C(R₇)═C(R₈)—*′, *—C(═S)—*′, and *—C≡C—*′,     -   L₇ and b7 are each independently the same as described in         connection with L₅ and b5,     -   R₇ and R₈ are each independently the same as described in         connection with R₅, and     -   * and *′ each indicate a binding site to a neighboring atom.

For example, T₅ may be selected from a single bond, *—N[(L₇)_(b7)-(R₇)]—*′, *—C(R₇)(R₅)—*′, *—Si(R₇)(R₅)—*′, *—S—*′, *—O—*′, and *—C(═O)—*′.

The organometallic compound represented by Formula 1 may be selected from Compounds 1 to 201, but embodiments of the present disclosure are not limited thereto:

The organometallic compound represented by Formula 1 does not include fluorine. Accordingly, the organometallic compound represented by Formula 1 has relatively excellent metal-to-ligand charge-transfer (MLCT) and thus may have a short decay rate.

Also, since a71 and a72 in Formula 1 are not zero, CY₁ in Formula 1 is substituted with R₇₁ and R₇₂ “at the same time” as described herein. Accordingly, an electronic device, for example, an organic light-emitting device, which includes the organometallic compound represented by Formula 1, may achieve improvement in efficiency and lifespan “at the same time”.

For example, a highest occupied molecular orbital (HOMO) energy level, a lowest unoccupied molecular orbital (LUMO) energy level, a singlet (S₁) energy level, and a triplet (T₁) energy level of some of Compounds and Compound A were evaluated by using a density functional theory (DFT) method of a Gaussian program (B3LYP, structurally optimized at a level of 6-31G(d,p)). Evaluation results thereof are shown in Table 1.

TABLE 1 Compound HOMO LUMO S₁ energy level T₁ energy level No. (eV) (eV) (eV) (eV) 1 −4.321 −1.591 2.165 1.951 2 −4.349 −1.675 2.121 1.915 4 −4.275 −1.566 2.144 1.932 5 −4.352 −1.618 2.176 1.956 7 −4.317 −1.672 2.122 1.924 9 −4.395 −1.674 2.153 1.939 17 −4.416 −1.687 2.175 1.956 18 −4.408 −1.682 2.726 1.951 21 −4.333 −1.603 2.156 1.931 26 −4.392 −1.731 2.119 1.921 55 −4.348 −1.734 2.093 1.899 59 −4.320 −1.657 2.131 1.933 78 −4.395 −1.725 2.128 1.938 79 −4.431 −1.671 2.191 1.976 87 −4.493 −1.744 2.177 1.960 92 −4.360 −1.699 2.100 1.885 101 −4.525 −1.826 2.140 1.914 102 −4.368 −1.708 2.099 1.886 103 −4.326 −1.671 2.095 1.886 104 −4.406 −1.788 2.095 1.906 127 −4.448 −1.683 2.194 1.977 128 −4.478 −1.768 2.151 1.941 148 −4.465 −1.677 2.206 1.982 155 −4.310 −1.672 2.113 1.916 A −4.419 −1.589 2.236 1.985

From Table 1, it can be determined that the organometallic compound represented by Formula 1 may be suitable for use in an electron device, for example, for use as a dopant for an organic light-emitting device.

Synthesis methods of the organometallic compound represented by Formula 1 may be recognizable by one of ordinary skill in the art by referring to Synthesis Examples provided below.

The organometallic compound represented by Formula 1 is suitable for use in an organic layer of an organic light-emitting device, for example, for use as a dopant in an emission layer of the organic layer. Thus, another aspect provides an organic light-emitting device that includes:

-   -   a first electrode;     -   a second electrode; and     -   an organic layer that is disposed between the first electrode         and the second electrode,     -   wherein the organic layer includes an emission layer and at         least one of the organometallic compound represented by Formula         1.

The organic light-emitting device may have, due to the inclusion of an organic layer including the organometallic compound represented by Formula 1, a low driving voltage, high efficiency, high power, high quantum efficiency, a long lifespan, a low roll-off ratio, and excellent color purity.

The organometallic compound represented by Formula 1 may be used between a pair of electrodes of an organic light-emitting device. For example, the organometallic compound represented by Formula 1 may be included in the emission layer. In this regard, the organometallic compound may act as a dopant, and the emission layer may further include a host (that is, an amount of the organometallic compound represented by Formula 1 is smaller than an amount of the host).

The expression “(an organic layer) includes at least one of organometallic compounds” as used herein may include an embodiment in which “(an organic layer) includes identical organometallic compounds represented by Formula 1” and an embodiment in which “(an organic layer) includes two or more different organometallic compounds represented by Formula 1.”

For example, the organic layer may include, as the organometallic compound, only Compound 1. In this embodiment, Compound 1 may be included in an emission layer of the organic light-emitting device. In one or more embodiments, the organic layer may include, as the organometallic compound, Compound 1 and Compound 2. In this embodiment, Compound 1 and Compound 2 may be included in an identical layer (for example, Compound 1 and Compound 2 may both be included in an emission layer).

The first electrode may be an anode, which is a hole injection electrode, and the second electrode may be a cathode, which is an electron injection electrode; or the first electrode may be a cathode, which is an electron injection electrode, and the second electrode may be an anode, which is a hole injection electrode.

In an embodiment, in the organic light-emitting device, the first electrode is an anode, and the second electrode is a cathode, and the organic layer further includes a hole transport region disposed between the first electrode and the emission layer and an electron transport region disposed between the emission layer and the second electrode, wherein the hole transport region includes a hole injection layer, a hole transport layer, an electron blocking layer, or any combination thereof, and wherein the electron transport region includes a hole blocking layer, an electron transport layer, an electron injection layer, or any combination thereof.

The term “organic layer” as used herein refers to a single layer and/or a plurality of layers disposed between the first electrode and the second electrode of the organic light-emitting device. The “organic layer” may include, in addition to an organic compound, an organometallic complex including metal.

The FIG. 1s a schematic view of an organic light-emitting device 10 according to an embodiment. Hereinafter, the structure of an organic light-emitting device according to an embodiment and a method of manufacturing an organic light-emitting device according to an embodiment will be described in connection with the FIGURE. The organic light-emitting device 10 includes a first electrode 11, an organic layer 15, and a second electrode 19, which are sequentially stacked.

A substrate may be additionally disposed under the first electrode 11 or above the second electrode 19. For use as the substrate, any substrate that is used in general organic light-emitting devices may be used, and the substrate may be a glass substrate or a transparent plastic substrate, each having excellent mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and water resistance.

The first electrode 11 may be formed by depositing or sputtering a material for forming the first electrode 11 on the substrate. The first electrode 11 may be an anode. The material for forming the first electrode 11 may be selected from materials with a high work function to facilitate hole injection. The first electrode 11 may be a reflective electrode, a semi-transmissive electrode, or a transmissive electrode. The material for forming the first electrode may be, for example, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO₂), and zinc oxide (ZnO). In one or more embodiments, magnesium (Mg), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), or magnesium-silver (Mg—Ag) may be used as the material for forming the first electrode.

The first electrode 11 may have a single-layered structure or a multi-layered structure including two or more layers. For example, the first electrode 11 may have a three-layered structure of ITO/Ag/ITO, but the structure of the first electrode 110 is not limited thereto.

The organic layer 15 is disposed on the first electrode 11.

The organic layer 15 may include a hole transport region, an emission layer, and an electron transport region.

The hole transport region may be disposed between the first electrode 11 and the emission layer.

The hole transport region may include a hole injection layer, a hole transport layer, an electron blocking layer, a buffer layer, or any combination thereof.

The hole transport region may include only either a hole injection layer or a hole transport layer. In one or more embodiments, the hole transport region may have a hole injection layer/hole transport layer structure or a hole injection layer/hole transport layer/electron blocking layer structure, which are sequentially stacked in this stated order from the first electrode 11.

A hole injection layer may be formed on the first electrode 11 by using one or more suitable methods selected from vacuum deposition, spin coating, casting, or Langmuir-Blodgett (LB) deposition.

When a hole injection layer is formed by vacuum deposition, the deposition conditions may vary according to a compound that is used to form the hole injection layer, and the structure and thermal characteristics of the hole injection layer. For example, the deposition conditions may include a deposition temperature of about 100° C. to about 500° C., a vacuum pressure of about 10⁻⁸ torr to about 10⁻³ torr, and a deposition rate of about 0.01 Angstroms per second (A/sec) to about 100 Å/sec, but embodiments of the present disclosure are not limited thereto.

When the hole injection layer is formed using spin coating, coating conditions may vary according to the material used to form the hole injection layer, and the structure and thermal properties of the hole injection layer. For example, a coating speed may be from about 2,000 revolutions per minute (rpm) to about 5,000 rpm, and a temperature at which a heat treatment is performed to remove a solvent after coating may be from about 80° C. to about 200° C. However, the coating conditions are not limited thereto.

Conditions for forming a hole transport layer and an electron blocking layer may be understood by referring to conditions for forming the hole injection layer.

The hole transport region may include at least one selected from m-MTDATA, TDATA, 2-TNATA, NPB, β-NPB, TPD, Spiro-TPD, Spiro-NPB, methylated-NPB, TAPC, HMTPD, 4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA), polyaniline/dodecylbenzene sulfonic acid (PANI/DBSA), poly(3,4-ethylenedioxythiophene)/poly(4-styrene sulfonate) (PEDOT/PSS), polyaniline/camphor sulfonic acid (PANI/CSA), polyaniline/poly(4-styrene sulfonate) (PANI/PSS), a compound represented by Formula 201 below, and a compound represented by Formula 202 below:

Ar₁₀₁ and Ar₁₀₂ in Formula 201 may each independently be selected from:

a phenylene group, a pentalenylene group, an indenylene group, a naphthylene group, an azulenylene group, a heptalenylene group, an acenaphthylene group, a fluorenylene group, a phenalenylene group, a phenanthrenylene group, an anthracenylene group, a fluoranthenylene group, a triphenylenylene group, a pyrenylene group, a chrysenylenylene group, a naphthacenylene group, a picenylene group, a perylenylene group, and a pentacenylene group; and

a phenylene group, a pentalenylene group, an indenylene group, a naphthylene group, an azulenylene group, a heptalenylene group, an acenaphthylene group, a fluorenylene group, a phenalenylene group, a phenanthrenylene group, an anthracenylene group, a fluoranthenylene group, a triphenylenylene group, a pyrenylene group, a chrysenylenylene group, a naphthacenylene group, a picenylene group, a perylenylene group, and a pentacenylene group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group.

In Formula 201, xa and xb may each independently be an integer from 0 to 5, or 0, 1, or 2. For example, xa is 1 and xb is 0, but xa and xb are not limited thereto.

R₁₀₁ to R₁₀₈, R₁₁₁ to R₁₁₉, and R₁₂₁ to R₁₂₄ in Formulae 201 and 202 may each independently be selected from:

hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group (for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and so on), or a C₁-C₁₀ alkoxy group (for example, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, and so on);

a C₁-C₁₀ alkyl group or a C₁-C₁₀ alkoxy group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, and a phosphoric acid group or a salt thereof;

a phenyl group, a naphthyl group, an anthracenyl group, a fluorenyl group, and a pyrenyl group; and

a phenyl group, a naphthyl group, an anthracenyl group, a fluorenyl group, and a pyrenyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group, and a C₁-C₁₀ alkoxy group, but embodiments of the present disclosure are not limited thereto.

R₁₀₉ in Formula 201 may be selected from:

a phenyl group, a naphthyl group, an anthracenyl group, and a pyridinyl group; and

a phenyl group, a naphthyl group, an anthracenyl group, and a pyridinyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, an anthracenyl group, and a pyridinyl group.

According to an embodiment, the compound represented by Formula 201 may be represented by Formula 201A, but embodiments of the present disclosure are not limited thereto:

R₁₀₁, R₁₁₁, R₁₁₂, and R₁₀₉ in Formula 201A may be understood by referring to the description provided herein.

For example, the compound represented by Formula 201, and the compound represented by Formula 202 may include compounds HT1 to HT20 illustrated below, but are not limited thereto.

A thickness of the hole transport region may be in a range of about 100 Angstroms (Å) to about 10,000 Å, for example, about 100 Å to about 1,000 Å. When the hole transport region includes at least one of a hole injection layer and a hole transport layer, the thickness of the hole injection layer may be in a range of about 100 Å to about 10,000 Å, and for example, about 100 Å to about 1,000 Å, and the thickness of the hole transport layer may be in a range of about 50 Å to about 2,000 Å, and for example, about 100 Å to about 1,500 Å. While not wishing to be bound by theory, it is understood that when the thicknesses of the hole transport region, the hole injection layer, and the hole transport layer are within these ranges, satisfactory hole transporting characteristics may be obtained without a substantial increase in driving voltage.

The hole transport region may further include, in addition to these materials, a charge-generation material for the improvement of conductive properties. The charge-generation material may be homogeneously or non-homogeneously dispersed in the hole transport region.

The charge-generation material may be, for example, a p-dopant. The p-dopant may be one selected from a quinone derivative, a metal oxide, and a compound including a cyano group, but embodiments of the present disclosure are not limited thereto. Non-limiting examples of the p-dopant are a quinone derivative, such as tetracyanoquinonedimethane (TCNQ) or 2,3,5,6-tetrafluoro-tetracyano-1,4-benzoquinonedimethane (F4-TCNQ); a metal oxide, such as a tungsten oxide or a molybdenium oxide; and a compound including a cyano group, such as Compound HT-D1 below, but are not limited thereto.

The hole transport region may include a buffer layer.

Also, the buffer layer may compensate for an optical resonance distance according to a wavelength of light emitted from the emission layer, and thus, efficiency of a formed organic light-emitting device may be improved.

Then, an emission layer may be formed on the hole transport region by vacuum deposition, spin coating, casting, LB deposition, or the like. When the emission layer is formed by vacuum deposition or spin coating, the deposition or coating conditions may be similar to those applied in forming the hole injection layer although the deposition or coating conditions may vary according to a compound that is used to form the emission layer.

Meanwhile, when the hole transport region includes an electron blocking layer, a material for the electron blocking layer may be selected from materials for the hole transport region described above and materials for a host to be explained later. However, the material for the electron blocking layer is not limited thereto. For example, when the hole transport region includes an electron blocking layer, a material for the electron blocking layer may be mCP, which will be explained later.

The emission layer may include a host and a dopant, and the dopant may include the organometallic compound represented by Formula 1.

The host may include at least one selected from TPBi, TBADN, ADN (also referred to as “DNA”), CBP, CDBP, TCP, mCP, Compound H50, and Compound H51:

In one or more embodiments, the host may further include a compound represented by Formula 301 below. Formula 301

Ar₁₁₁ and Ar₁₁₂ in Formula 301 may each independently be selected from:

a phenylene group, a naphthylene group, a phenanthrenylene group, and a pyrenylene group; and

a phenylene group, a naphthylene group, a phenanthrenylene group, and a pyrenylene group, each substituted with at least one selected from a phenyl group, a naphthyl group, and an anthracenyl group.

Ar₁₁₃ to Ar₁₁₆ in Formula 301 may each independently be selected from:

a C₁-C₁₀ alkyl group, a phenyl group, a naphthyl group, a phenanthrenyl group, and a pyrenyl group; and

a phenyl group, a naphthyl group, a phenanthrenyl group, and a pyrenyl group, each substituted with at least one selected from a phenyl group, a naphthyl group, and an anthracenyl group.

g, h, i, and j in Formula 301 may each independently be an integer from 0 to 4, and may be, for example, 0, 1, or 2.

Ar₁₁₃ to Ar₁₁₆ in Formula 301 may each independently be selected from

a C₁-C₁₀ alkyl group, substituted with at least one selected from a phenyl group, a naphthyl group, and an anthracenyl group;

a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl, a phenanthrenyl group, and a fluorenyl group;

a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, a phenanthrenyl group, and a fluorenyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, a phenanthrenyl group, and a fluorenyl group; and

but embodiments of the present disclosure are not limited thereto.

In one or more embodiments, the host may include a compound represented by Formula 302 below:

Ar₁₂₂ to Ar₁₂₅ in Formula 302 are the same as described in detail in connection with Ar₁₁₃ in Formula 301.

Ar₁₂₆ and Ar₁₂₇ in Formula 302 may each independently be a C₁-C₁₀ alkyl group (for example, a methyl group, an ethyl group, or a propyl group).

k and l in Formula 302 may each independently be an integer from 0 to 4. For example, k and l may be 0, 1, or 2.

The compound represented by Formula 301 and the compound represented by Formula 302 may include Compounds H1 to H42 illustrated below, but are not limited thereto.

When the organic light-emitting device is a full-color organic light-emitting device, the emission layer may be patterned into a red emission layer, a green emission layer, and a blue emission layer. In one or more embodiments, due to a stacked structure including a red emission layer, a green emission layer, and/or a blue emission layer, the emission layer may emit white light.

When the emission layer includes a host and a dopant, an amount of the dopant may be in a range of about 0.01 parts by weight to about 15 parts by weight based on 100 parts by weight of the host, but embodiments of the present disclosure are not limited thereto.

A thickness of the emission layer may be in a range of about 100 Å to about 1,000 Å, for example, about 200 Å to about 600 Å. While not wishing to be bound by theory, it is understood that when the thickness of the emission layer is within this range, excellent light-emission characteristics may be obtained without a substantial increase in driving voltage.

Then, an electron transport region may be disposed on the emission layer.

The electron transport region may include a hole blocking layer, an electron transport layer, an electron injection layer, or any combination thereof.

For example, the electron transport region may have a hole blocking layer/electron transport layer/electron injection layer structure or an electron transport layer/electron injection layer structure, but the structure of the electron transport region is not limited thereto. The electron transport layer may have a single-layered structure or a multi-layered structure including two or more different materials.

Conditions for forming the hole blocking layer, the electron transport layer, and the electron injection layer which constitute the electron transport region may be understood by referring to the conditions for forming the hole injection layer.

When the electron transport region includes a hole blocking layer, the hole blocking layer may include, for example, at least one of BCP, Bphen, and BAlq but embodiments of the present disclosure are not limited thereto.

A thickness of the hole blocking layer may be in a range of about 20 Å to about 1,000 Å, for example, about 30 Å to about 300 Å. While not wishing to be bound by theory, it is understood that when the thickness of the hole blocking layer is within these ranges, the hole blocking layer may have improved hole blocking ability without a substantial increase in driving voltage.

The electron transport layer may further include at least one selected from BCP, Bphen, Alq₃, BAlq, TAZ, and NTAZ.

In one or more embodiments, the electron transport layer may include at least one of ET1 and ET2, but are not limited thereto:

A thickness of the electron transport layer may be in a range of about 100 to about 1,000 Å, for example, about 150 Å to about 500 Å. While not wishing to be bound by theory, it is understood that when the thickness of the electron transport layer is within the range described above, the electron transport layer may have satisfactory electron transport characteristics without a substantial increase in driving voltage.

Also, the electron transport layer may further include, in addition to the materials described above, a metal-containing material.

The metal-containing material may include a Li complex. The Li complex may include, for example, Compound ET-D1 (lithium quinolate, LiQ) or ET-D2.

The electron transport region may include an electron injection layer) that promotes flow of electrons from the second electrode 19 thereinto.

The electron injection layer may include at least one selected from LiF, NaCl, CsF, Li₂O, and BaO.

A thickness of the electron injection layer may be in a range of about 1 Å to about 100 Å, for example, about 3 Å to about 90 Å. While not wishing to be bound by theory, it is understood that when the thickness of the electron injection layer is within the range described above, the electron injection layer may have satisfactory electron injection characteristics without a substantial increase in driving voltage.

The second electrode 19 is disposed on the organic layer 15. The second electrode 19 may be a cathode. A material for forming the second electrode 19 may be selected from metal, an alloy, an electrically conductive compound, and a combination thereof, which have a relatively low work function. For example, lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), or magnesium-silver (Mg—Ag) may be used as a material for forming the second electrode 19. In one or more embodiments, to manufacture a top-emission type light-emitting device, a transmissive electrode formed using ITO or IZO may be used as the second electrode 19.

Hereinbefore, the organic light-emitting device has been described with reference to the FIGURE, but embodiments of the present disclosure are not limited thereto.

Another aspect of the present disclosure provides a diagnostic composition including at least one organometallic compound represented by Formula 1.

The organometallic compound represented by Formula 1 provides high luminescent efficiency. Accordingly, a diagnostic composition including the organometallic compound may have high diagnostic efficiency.

The diagnostic composition may be used in various applications including a diagnosis kit, a diagnosis reagent, a biosensor, and a biomarker.

The term “C₁-C₆₀ alkyl group” as used herein refers to a linear or branched saturated aliphatic hydrocarbon monovalent group having 1 to 60 carbon atoms, and non-limiting examples thereof include a methyl group, an ethyl group, a propyl group, an iso-butyl group, a sec-butyl group, a tert-butyl group, pentyl group, an iso-amyl group, and a hexyl group. The term “C₁-C₆₀ alkylene group” as used herein refers to a divalent group having the same structure as the C₁-C₆₀ alkyl group.

The term “C₁-C₆₀ alkoxy group” as used herein refers to a monovalent group represented by —OA₁₀₁ (wherein A₁₀₁ is the C₁-C₆₀ alkyl group), and non-limiting examples thereof include a methoxy group, an ethoxy group, and an iso-propyloxy (isopropoxy) group.

The term “C₂-C₆₀ alkenyl group” as used herein refers to a hydrocarbon group formed by including at least one carbon-carbon double bond in the middle or at the terminus of the C₂-C₆₀ alkyl group, and examples thereof include an ethenyl group, a propenyl group, and a butenyl group. The term “C₂-C₆₀ alkenylene group” as used herein refers to a divalent group having the same structure as the C₂-C₆₀ alkenyl group.

The term “C₂-C₆₀ alkynyl group” as used herein refers to a hydrocarbon group formed by including at least one carbon-carbon triple bond in the middle or at the terminus of the C₂-C₆₀ alkyl group, and examples thereof include an ethynyl group, and a propynyl group. The term “C₂-C₆₀ alkynylene group” as used herein refers to a divalent group having the same structure as the C₂-C₆₀ alkynyl group.

The term “C₃-C₁₀ cycloalkyl group” as used herein refers to a monovalent saturated hydrocarbon monocyclic group having 3 to 10 carbon atoms, and non-limiting examples thereof include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group. The term “C₃-C₁₀ cycloalkylene group” as used herein refers to a divalent group having the same structure as the C₃-C₁₀ cycloalkyl group.

The term “C₁-C₁₀ heterocycloalkyl group” as used herein refers to a monovalent saturated monocyclic group having at least one heteroatom selected from N, O, P, Si and S as a ring-forming atom and 1 to 10 carbon atoms, and non-limiting examples thereof include a tetrahydrofuranyl group, and a tetrahydrothiophenyl group. The term “C₁-C₁₀ heterocycloalkylene group” as used herein refers to a divalent group having the same structure as the C₁-C₁₀ heterocycloalkyl group.

The term “C₃-C₁₀ cycloalkenyl group” as used herein refers to a monovalent monocyclic group that has 3 to 10 carbon atoms and at least one carbon-carbon double bond in the ring thereof and that has no aromaticity, and non-limiting examples thereof include a cyclopentenyl group, a cyclohexenyl group, and a cycloheptenyl group. The term “C₃-C₁₀ cycloalkenylene group” as used herein refers to a divalent group having the same structure as the C₃-C₁₀ cycloalkenyl group.

The term “C₁-C₁₀ heterocycloalkenyl group” as used herein refers to a monovalent monocyclic group that has at least one heteroatom selected from N, O, P, Si, and S as a ring-forming atom, 1 to 10 carbon atoms, and at least one carbon-carbon double bond in its ring. Examples of the C₁-C₁₀ heterocycloalkenyl group are a 2,3-dihydrofuranyl group, and a 2,3-dihydrothiophenyl group. The term “C₁-C₁₀ heterocycloalkenylene group” as used herein refers to a divalent group having the same structure as the C₁-C₁₀ heterocycloalkenyl group.

The term “C₆-C₆₀ aryl group” as used herein refers to a monovalent group having a carbocyclic aromatic system having 6 to 60 carbon atoms, and the term “C₆-C₆₀ arylene group” as used herein refers to a divalent group having a carbocyclic aromatic system having 6 to 60 carbon atoms. Non-limiting examples of the C₆-C₆₀ aryl group include a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a pyrenyl group, and a chrysenyl group. When the C₆-C₆₀ aryl group and the C₆-C₆₀ arylene group each include two or more rings, the rings may be fused to each other.

The term “C₁-C₆₀ heteroaryl group” as used herein refers to a monovalent group having a carbocyclic aromatic system that has at least one heteroatom selected from N, O, P, Si, and S as a ring-forming atom, and 1 to 60 carbon atoms. The term “C₁-C₆₀ heteroarylene group” as used herein refers to a divalent group having a carbocyclic aromatic system that has at least one heteroatom selected from N, O, P, and S as a ring-forming atom, and 1 to 60 carbon atoms. Non-limiting examples of the C₁-C₆₀ heteroaryl group include a pyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, and an isoquinolinyl group.

When the C₁-C₆₀ heteroaryl group and the C₁-C₆₀ heteroarylene group each include two or more rings, the rings may be fused to each other.

The term “C₆-C₆₀ aryloxy group” as used herein indicates —OA₁₀₂ (wherein A₁₀₂ is the C₆-C₆₀ aryl group), and a C₆-C₆₀ arylthio group as used herein indicates —SA₁₀₃ (wherein A₁₀₃ is the C₆-C₆₀ aryl group).

The term “monovalent non-aromatic condensed polycyclic group” as used herein refers to a monovalent group (for example, having 8 to 60 carbon atoms) having two or more rings condensed to each other, only carbon atoms as ring-forming atoms, and having no aromaticity in its entire molecular structure. Examples of the monovalent non-aromatic condensed polycyclic group include a fluorenyl group. The term “divalent non-aromatic condensed polycyclic group,” as used herein, refers to a divalent group having the same structure as the monovalent non-aromatic condensed polycyclic group.

The term “monovalent non-aromatic condensed heteropolycyclic group” as used herein refers to a monovalent group (for example, having 2 to 60 carbon atoms) having two or more rings condensed to each other, a heteroatom selected from N, O, P, Si, and S, other than carbon atoms, as a ring-forming atom, and having no aromaticity in its entire molecular structure. Non-limiting examples of the monovalent non-aromatic condensed heteropolycyclic group include a carbazolyl group. The term “divalent non-aromatic condensed heteropolycyclic group” as used herein refers to a divalent group having the same structure as the monovalent non-aromatic condensed heteropolycyclic group.

The term “C₅-C₃₀ carbocyclic group” as used herein refers to a saturated or unsaturated cyclic group having, as a ring-forming atom, 5 to 30 carbon atoms only. The C₅-C₃₀ carbocyclic group may be a monocyclic group or a polycyclic group.

The term “C₁-C₃₀ heterocyclic group” as used herein refers to a saturated or unsaturated cyclic group having, as a ring-forming atom, at least one heteroatom selected from N, O, Si, P, and S other than 1 to 30 carbon atoms. The C₁-C₃₀ heterocyclic group may be a monocyclic group or a polycyclic group.

At least one substituent of the substituted C₅-C₃₀ carbocyclic group, the substituted C₂-C₃₀ heterocyclic group, the substituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀ alkenyl group, the substituted C₂-C₆₀ alkynyl group, the substituted C₁-C₆₀ alkoxy group, the substituted C₃-C₁₀ cycloalkyl group, the substituted C₁-C₁₀ heterocycloalkyl group, the substituted C₃-C₁₀ cycloalkenyl group, the substituted C₁-C₁₀ heterocycloalkenyl group, the substituted C₆-C₆₀ aryl group, the substituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀ arylthio group, the substituted C₇-C₆₀ arylalkyl group, the substituted C₁-C₆₀ heteroaryl group, the substituted C₁-C₆₀ heteroaryloxy group, the substituted C₁-C₆₀ heteroarylthio group, the substituted C₂-C₆₀ heteroarylalkyl group, the substituted monovalent non-aromatic condensed polycyclic group, and the substituted monovalent non-aromatic condensed heteropolycyclic group may be selected from:

deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy group; a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group,

a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —N(Q₁₁)(Q₁₂), —Si(Q₁₃)(Q₁₄)(Q₁₅), —B(Q₁₆)(Q₁₇), and —P(═O)(Q₁₈)(Q₁₉);

-   -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a         C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a         C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic         condensed polycyclic group, and a monovalent non-aromatic         condensed heteropolycyclic group;     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a         C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a         C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic         condensed polycyclic group, and a monovalent non-aromatic         condensed heteropolycyclic group, each substituted with at least         one selected from deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H,         —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a         nitro group, an amino group, an amidino group, a hydrazine         group, a hydrazone group, a carboxylic acid group or a salt         thereof, a sulfonic acid group or a salt thereof, a phosphoric         acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀         alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a         C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a         C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a         C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic         condensed polycyclic group, a monovalent non-aromatic condensed         heteropolycyclic group, —N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅),         —B(Q₂₆)(Q₂₇), and —P(═O)(Q₂₈)(Q₂₉); and

—N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅), —B(Q₃₆)(Q₃₇), and —P(═O)(Q₃₈)(Q₃₉), wherein

Q₁ to Q₉, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, and Q₃₁ to Q₃₉ may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryl group substituted with at least one selected from a C₁-C₆₀ alkyl group, and a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group.

Hereinafter, a compound and an organic light-emitting device according to embodiments are described in detail with reference to Synthesis Examples and Examples. However, the organic light-emitting device is not limited thereto. The wording “B was used instead of A” used in describing Synthesis Examples means that an amount of A used was identical to an amount of B used, in terms of molar equivalents.

EXAMPLES Synthesis Example 1: Synthesis of Compound 1 Synthesis of Intermediate 1-2

4.03 grams (g) (20.1 millimoles, mmol) of 2-bromo-5-methyl-4-phenylpyridine (Intermediate 1-3) was mixed with 100 milliliters (mL) of toluene, 30 mL of ethanol, and 30 mL of water. To this mixture, 7.20 g (20.1 mmol) of (3-bromophenyl)boronic acid, 1.62 g (1.40 mmol) of palladium catalyst, and 5.28 g (50.1 mmol) of sodium carbonate were added. The resultant mixture was heated under reflux at a temperature of 120° C. for 18 hours. The product was concentrated under reduced pressure, mixed with 400 mL of dichloromethane, and filtered by using diatomite. The organic layer was dried over magnesium sulfate, and the solvent was removed under reduced pressure. The residue was purified by liquid chromatography to obtain 4.55 g (yield: 70%) of Intermediate 1-2.

LC-MS m/z=314 (M+H)⁺.

Synthesis of Intermediate 1-1

6.58 g (20.3 mmol) of Intermediate 1-2 was mixed with 100 mL of toluene. To this mixture, 1.43 g (8.45 mmol) of [1,1′-biphenyl]-2-amine, 0.49 g (0.85 mmol) of Pd(dba)₂, 1.1 g (2.54 mmol) of P(tBu)₃, and 2.03 g (21.1 mmol) of sodium butoxide were added. The resultant mixture was heated under reflux at a temperature of 130° C. for 24 hours. The product was concentrated under reduced pressure and mixed with 200 mL of dichloromethane. The organic layer was dried by using magnesium sulfate, and the solvent was removed under reduced pressure. The residue was purified by liquid (M+H)⁺.

Synthesis of Compound 1

2.10 g (3.2 mmol) of Intermediate 1-1 was mixed with 130 mL of benzonitrile at room temperature, and 1.51 g (3.20 mmol) of PtCl₂(NCPh)₂ was added thereto. The resultant mixture was heated under reflux at a temperature of 150° C. for 18 hours. After the completion of reaction was confirmed by LCMS, the reaction mixture was concentrated under reduced pressure and purified by liquid chromatography to obtain 0.6 g (yield: 28%) of Compound 1. Compound 1 was identified by Mass and HPLC.

HRMS (MALDI) calcd for C₄₈H₃₅N₃Pt: m/z 848.2479, Found: 848.2477.

Synthesis Example 2: Synthesis of Compound 2 Synthesis of Intermediate 2-2

5.50 g (17.0 mmol) of Intermediate 1-2 was mixed with 80 mL of toluene. To this mixture, 2.87 g (17.0 mmol) of [1,1′-biphenyl]-2-amine, 0.976 g (1.7 mmol) of Pd(dba)₂, 2.06 g (0.30 mmol) of P(tBu)₃, and 4.89 g (50.9 mmol) of sodium butoxide were added. The resultant mixture was heated under reflux at a temperature 130° C. for 18 hours. The product was concentrated under reduced pressure, mixed with 200 mL of dichloromethane, and filtered by using diatomite. The organic layer was dried by using magnesium sulfate, and the solvent was removed under reduced pressure.

Then, the residue was purified by liquid chromatography to obtain 4.3 g (yield: 61%) of Intermediate 2-2. LC-MS m/z=413 (M+H)⁺.

Synthesis of Intermediate 2-1

3.5 g (78%) of Intermediate 2-1 was synthesized in the same manner as Intermediate 1-1 in Synthesis Example 1, except that 2.88 g (7.00 mmol) of Intermediate 2-2 and 2.83 g (9.1 mmol) of 2-(3-bromophenyl)-4-phenylpyridine (Intermediate 2-3) were each used instead of Intermediate 1-2 and [1,1′-biphenyl]-2-amine.

LC-MS m/z=642 (M+H)⁺.

Synthesis of Compound 2

0.40 g (24%) of Compound 2 was synthesized in the same manner as Compound 1 in Synthesis Example 1, except that 1.28 g (2.00 mmol) of Intermediate 2-1 was used instead of Intermediate 1-1. Compound 2 was identified by Mass and HPLC.

HRMS (MALDI) calcd for C₄₇H₃₃N₃Pt: m/z 834.2322, Found: 834.2322.

Synthesis Example 3: Synthesis of Compound 4 Synthesis of Intermediate 4-2

3.9 g (85%) of Intermediate 4-2 was synthesized in the same manner as Intermediate 1-2 in Synthesis Example 1, except that 3.42 g (13.3 mmol) of β-bromo-5-(tert-butyl)phenyl)boronic acid was used instead of (3-bromophenyl)boronic acid.

LC-MS m/z=380 (M+H)⁺.

Synthesis of Intermediate 4-1

2.94 g (79%) of Intermediate 4-1 was synthesized in the same manner as Intermediate 1-1 in Synthesis Example 1, except that 0.825 g (4.88 mmol) of Intermediate 4-2 was used instead of Intermediate 1-2.

LC-MS m/z=768 (M+H)⁺.

Synthesis of Compound 4

0.43 g (12%) of Compound 4 was synthesized in the same manner as Compound 1 in Synthesis Example 1, except that 2.94 g (3.83 mmol) of Intermediate 4-1 was used instead of Intermediate 1-1. Compound 4 was identified by Mass and HPLC.

HRMS (MALDI) calcd for C₅₆H₅₁N₃Pt: m/z 960.3731, Found: 960.3730.

Synthesis Example 4: Synthesis of Compound 7 Synthesis of Intermediate 7-1

2.80 g (58%) of Intermediate 7-1 was synthesized in the same manner as Intermediate 1-1 in Synthesis Example 1, except that 5.57 g (14.9 mmol) of Intermediate 7-2 was used instead of Intermediate 1-2.

LC-MS m/z=756 (M+H)⁺.

Synthesis of Compound 7

0.90 g (26%) of Compound 7 was synthesized in the same manner as Compound 1 in Synthesis Example 1, except that 2.76 g (3.65 mmol) of Intermediate 7-1 was used instead of Intermediate 1-1. Compound 7 was identified by Mass and HPLC.

HRMS (MALDI) calcd for C₅₆H₃₉N₃Pt: m/z 948.2792, Found: 948.2790.

Synthesis Example 5: Synthesis of Compound 9 Synthesis of Intermediate 9-3

17.1 g (54.9 mmol) of Intermediate 9-4 and 550 mL of tetrahydrofuran (THF) were mixed, and the mixture was stirred at a temperature of −78° C. for 10 minutes. To this mixture, n-butyllithium (23.0 mL of a 2.5 M solution in hexanes, 57.6 mmol) was slowly added by drops for 30 minutes, and the resultant mixture was stirred at a temperature of −78° C. for 4 hours. Then, 12.3 mL (60.4 mmol) of 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane was added thereto, and after 15 minutes, the resultant mixture was warmed to room temperature and stirred for 5 hours. 200 mL of distilled water was added thereto, and the resultant mixture was stirred. Then, methylene chloride (200 mL×3) was added thereto. The organic layer was dried by using MgSO₄, and the solvent was evaporated. The residue was purified by liquid chromatography to obtain 9.0 g (yield: 46%) of Intermediate 9-3. MALDI-TOF m/z=359 (M+H)⁺.

Synthesis of Intermediate 9-2

4.55 g (85%) of Intermediate 9-2 was synthesized in the same manner as Intermediate 1-2 in Synthesis Example 1, except that 5.83 g (16.2 mmol) of Intermediate 9-3 was used instead of (3-bromophenyl)boronic acid.

LC-MS m/z=400 (M+H)⁺.

Synthesis of Intermediate 9-1

2.30 g (61%) of Intermediate 9-1 was synthesized in the same manner as Intermediate 1-1 in Synthesis Example 1, except that 4.52 g (11.3 mmol) of Intermediate 9-2 was used instead of Intermediate 1-2.

LC-MS m/z=808 (M+H)⁺.

Synthesis of Compound 9

0.30 g (11%) of Compound 9 was synthesized in the same manner as Compound 1 in Synthesis Example 1, except that 2.30 g (2.87 mmol) of Intermediate 9-1 was used instead of Intermediate 1-1. Compound 9 was identified by Mass and HPLC.

HRMS (MALDI) calcd for C₆₀H₄₃N₃Pt: m/z 1000.3105, Found: 1000.3105.

Synthesis Example 6: Synthesis of Compound 17 Synthesis of Intermediate 17-2

4.11 g (59%) of Intermediate 17-2 was synthesized in the same manner as Intermediate 2-2 in Synthesis Example 2, except that 5.45 g (17.6 mmol) of Intermediate 17-3 was used instead of Intermediate 1-2.

LC-MS m/z=399 (M+H)⁺.

Synthesis of Intermediate 17-1

2.4 g (64%) of Intermediate 17-1 was synthesized in the same manner as Intermediate 2-1 in Synthesis Example 2, except that 2.07 g (5.20 mmol) of Intermediate 17-2 and 3.12 g (7.80 mmol) of Intermediate 17-4 were each used instead of Intermediate 2-2 and Intermediate 2-3.

LC-MS m/z=718 (M+H)⁺.

Synthesis of Compound 17

1.2 g (41%) of Compound 17 was synthesized in the same manner as Compound 1 in Synthesis Example 1, except that 2.30 g (2.87 mmol) of Intermediate 17-1 was used instead of Intermediate 1-1. Compound 17 was identified by Mass and HPLC.

HRMS (MALDI) calcd for C₅₃H₃₇N₃Pt: m/z 910.2635, Found: 910.2633.

Synthesis Example 7: Synthesis of Compound 18 Synthesis of Intermediate 18-4

2.70 g (59%) of Intermediate 18-4 was synthesized in the same manner as Intermediate 2-2 in Synthesis Example 2, except that 4.77 g (14.3 mmol) of Intermediate 18-5 was used instead of Intermediate 1-2.

LC-MS m/z=323 (M+H)⁺.

Synthesis of Intermediate 18-2

2.50 g (50%) of Intermediate 18-2 was synthesized in the same manner as Intermediate 1-2 in Synthesis Example 1, except that Intermediate 18-3 and 4.33 g (12.1 mmol) of Intermediate 9-3 were each used instead of Intermediate 1-3 and (3-bromophenyl)boronic acid.

LC-MS m/z=476 (M+H)⁺.

Synthesis of Intermediate 18-1

2.47 g (62%) of Intermediate 18-1 was synthesized in the same manner as Intermediate 2-1 in Synthesis Example 2, except that 1.78 g (5.57 mmol) of Intermediate 18-4 and 2.65 g (5.57 mmol) of Intermediate 18-2 were each used instead of Intermediate 2-2 and Intermediate 2-3.

LC-MS m/z=718 (M+H)⁺.

Synthesis of Compound 18

1.1 g (50%) of Compound 18 was synthesized in the same manner as Compound 1 in Synthesis Example 1, except that 1.73 g (2.41 mmol) of Intermediate 18-1 was used instead of Intermediate 1-1. Compound 18 was identified by Mass and HPLC.

HRMS (MALDI) calcd for C₅₃H₃₇N₃Pt: m/z 910.2635, Found: 910.2634.

Synthesis Example 8: Synthesis of Compound 21 Synthesis of Intermediate 21-2

4.55 g (70%) of Intermediate 21-2 was synthesized in the same manner as Intermediate 1-2 in Synthesis Example 1, except that 2-bromo-4-phenyl-5-(trimethylsilyl)pyridine and 5.21 g (17 mmol) of Intermediate 21-3 were each used instead of 2-bromo-5-methyl-4-phenylpyridine and Intermediate 1-2.

LC-MS m/z=382 (M+H)⁺.

Synthesis of Intermediate 21-1

2.45 g (61%) of Intermediate 21-1 was synthesized in the same manner as Intermediate 2-1 in Synthesis Example 2, except that 2.31 g (5.60 mmol) of Intermediate 2-2 and 2.14 g (5.60 mmol) of Intermediate 21-2 were each used instead of Intermediate 2-2 and Intermediate 2-3.

LC-MS m/z=714 (M+H)⁺.

Synthesis of Compound 21

1.10 g (37%) of Compound 21 was synthesized in the same manner as Compound 1 in Synthesis Example 1, except that 2.31 g (3.31 mmol) of Intermediate 21-1 was used instead of Intermediate 1-1. Compound 21 was identified by Mass and HPLC.

HRMS (MALDI) calcd for C₄₈H₃₅N₃Pt: m/z 848.2479, Found: 848.2478.

Synthesis Example 9: Synthesis of Compound 26 Synthesis of Intermediate 26-1

2.04 g (61%) of Intermediate 26-1 was synthesized in the same manner as Intermediate 1-1 in Synthesis Example 1, except that 4.06 g (8.52 mmol) of Intermediate 17-2 was used instead of Intermediate 1-2.

LC-MS m/z=960 (M+H)⁺.

Synthesis of Compound 26

0.70 g (43%) of Compound 26 was synthesized in the same manner as Compound 1 in Synthesis Example 1, except that 1.34 g (1.4 mmol) of Intermediate 26-1 was used instead of Intermediate 1-1. Compound 26 was identified by Mass and HPLC.

HRMS (MALDI) calcd for C₇₂H₅₁N₃Pt: m/z 1152.3731, Found: 1152.3732.

Synthesis Example 10: Synthesis of Compound 55 Synthesis of Intermediate 55-2

4.54 g (63%) of Intermediate 55-2 was synthesized in the same manner as Intermediate 2-2 in Synthesis Example 2, except that 4.62 g (12 mmol) of Intermediate 55-3 and 2.69 g (15.0 mmol) of naphthalen-1-amine were each used instead of Intermediate 1-2 and [1,1′-biphenyl]-2-amine.

LC-MS m/z=478 (M+H)⁺.

Synthesis of Intermediate 55-1

1.41 g (60%) of Intermediate 55-1 was synthesized in the same manner as Intermediate 2-1 in Synthesis Example 2, except that 1.53 g (3.40 mmol) of Intermediate 55-2 and 1.43 g (4.42 mmol) of Intermediate 1-2 were each used instead of Intermediate 2-2 and Intermediate 2-3.

LC-MS m/z=692 (M+H)⁺.

Synthesis of Compound 55

0.7 g (26%) of Compound 55 was synthesized in the same manner as Compound 1 in Synthesis Example 1, except that 2.11 g (3.05 mmol) of Intermediate 55-1 was used instead of Intermediate 1-1. Compound 55 was identified by Mass and HPLC.

HRMS (MALDI) calcd for C₅₁H₃₅N₃Pt: m/z 884.2479, Found: 884.2478.

Synthesis Example 11: Synthesis of Compound 59 Synthesis of Intermediate 59-1

1.80 g (57%) of Intermediate 59-1 was synthesized in the same manner as Intermediate 1-1 in Synthesis Example 1, except that Intermediate 7-2 and 0.72 g (4.00 mmol) of naphthalen-1-amine were each used instead of Intermediate 1-2 and [1,1′-biphenyl]-2-amine.

LC-MS m/z=782 (M+H)⁺.

Synthesis of Compound 59

0.60 g (49%) of Compound 59 was synthesized in the same manner as Compound 1 in Synthesis Example 1, except that 0.98 g (1.25 mmol) of Intermediate 59-1 was used instead of Intermediate 1-1. Compound 59 was identified by Mass and HPLC.

HRMS (MALDI) calcd for C₅₄H₃₇N₃Pt: m/z 922.2635, Found: 922.2634.

Synthesis Example 12: Synthesis of Compound 78 Synthesis of Intermediate 78-1

1.80 g (86%) of Intermediate 78-1 was synthesized in the same manner as Intermediate 1-1 in Synthesis Example 1, except that 2.35 g (4.96 mmol) of Intermediate 17-2 and 0.40 g (2.44 mmol) of naphthalen-1-amine were each used instead of Intermediate 1-2 and [1,1′-biphenyl]-2-amine.

LC-MS m/z=935 (M+H)⁺.

Synthesis of Compound 78

1.3 g (62%) of Compound 78 was synthesized in the same manner as Compound 1 in Synthesis Example 1, except that 1.74 g (1.86 mmol) of Intermediate 78-1 was used instead of Intermediate 1-1. Compound 78 was identified by Mass and HPLC.

HRMS (MALDI) calcd for C₇₀H₄₉N₃Pt: m/z 1126.3574, Found: 1126.3572.

Synthesis Example 13: Synthesis of Compound 127 Synthesis of Intermediate 127-1

1.80 g (45%) of Intermediate 127-1 was synthesized in the same manner as Intermediate 1-1 in Synthesis Example 1, except that 1.47 g (5.18 mmol) of 4-(9H-carbazol-9-yl)-2,6-dimethylaniline was used instead of [1,1′-biphenyl]-2-amine.

LC-MS m/z=773 (M+H)⁺.

Synthesis of Compound 127

0.80 g (38%) of Compound 127 was synthesized in the same manner as Compound 1 in Synthesis Example 1, except that 1.73 g (2.24 mmol) of Intermediate 127-1 was used instead of Intermediate 1-1. Compound 127 was identified by Mass and HPLC.

HRMS (MALDI) calcd for C₅₅H₄₂N₃Pt: m/z 965.3057, Found: 965.3053.

Synthesis Example 14: Synthesis of Compound 155 Synthesis of Intermediate 155-1

2.00 g (53%) of Intermediate 155-1 was synthesized in the same manner as Intermediate 1-1 in Synthesis Example 1, except that Intermediate 7-2 and 0.947 g (4.80 mmol) of 3,5-dimethyl-[1,1′-biphenyl]-2-amine were each used instead of Intermediate 1-2 and [1,1′-biphenyl]-2-amine.

LC-MS m/z=785 (M+H)⁺.

Synthesis of Compound 155

0.60 g (27%) of Compound 155 was synthesized in the same manner as Compound 1 in Synthesis Example 1, except that 1.83 g (2.30 mmol) of Intermediate 155-1 was used instead of Intermediate 1-1. Compound 155 was identified by Mass and HPLC.

HRMS (MALDI) calcd for C₅₈H₄₃N₃Pt: m/z 976.3105, Found: 976.3101.

Example 1

As an anode, a glass substrate, on which ITO/Ag/ITO were respectively deposited to have thicknesses of 70 Å/1,000 Å/70 Å, was cut to a size of 50 mm×50 mm×0.5 mm (mm=millimeters), sonicated with iso-propyl alcohol and pure water each for 5 minutes, and then cleaned by exposure to ultraviolet (UV) rays and ozone for 30 minutes. Then, the glass substrate was provided to a vacuum deposition apparatus.

2-TNATA was deposited on the anode to form a hole injection layer having a thickness of 600 Å, and 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB) was deposited on the hole injection layer to form a hole transport layer having a thickness of 1,350 Å.

CBP (host) and Compound 1 (dopant) were co-deposited on the hole transport layer at a weight ratio of 98:2 to form an emission layer having a thickness of 400 Å, and BCP was deposited on the emission layer to form a hole blocking layer having a thickness of 50 Å. Then, Alq₃ was deposited on the hole blocking layer to form an electron transport layer having a thickness of 350 Å, LiF was deposited on the electron transport layer to form an electron injection layer having a thickness of 10 Å, and MgAg was deposited on the electron injection layer at a weight ratio of 90:10 to form a cathode having a thickness of 120 Å, thereby completing the manufacture of an organic light-emitting device.

Examples 2 to 14 and Comparative Examples 1 to 3

Organic light-emitting devices were manufactured in the same manner as in Example 1, except that Compounds shown in Table 2 were each used instead of Compound 1 as a dopant in forming an emission layer.

Evaluation Example 1: Evaluation of Characteristics of Organic Light-Emitting Devices

The driving voltage, quantum emission efficiency, lifespan characteristics, and maximum emission wavelength of organic light-emitting devices manufactured according to Examples 1 to 14 and Comparative Examples 1 to 3 were evaluated by using a current-voltage meter (Keithley 2400) and a luminance meter (Minolta Cs-1000A), and results thereof are shown in Table 2. The lifespan (T₉₇) indicates an amount of time that lapsed when luminance was 97% of initial luminance (100%). The driving voltage, quantum emission efficiency, and lifespan of Examples 1 to 14 and Comparative Examples 1 and 2 are relative values when the driving voltage, quantum emission efficiency, and lifespan of Comparative Example 3 were 100%.

TABLE 2 Quantum emission Dopant compound Driving voltage efficiency (EQE) Lifespan (T₉₇) Maximum emission No. No. (%, relative value) (%, relative value) (%, relative value) wavelength (nm) Example 1 1 83 126 556 615 Example 2 2 87 125 483 629 Example 3 4 69 125 250 620 Example 4 7 78 133 500 621 Example 5 9 78 136 556 623 Example 6 17 88 126 400 617 Example 7 18 70 123 294 618 Example 8 21 75 123 211 623 Example 9 26 72 144 444 625 Example 10 55 71 132 389 627 Example 11 59 70 140 633 619 Example 12 78 70 137 361 630 Example 13 127 74 126 339 612 Example 14 155 77 133 222 623 Comparative A 84 122 170 607 Example 1 Comparative B 97 121 167 645 Example 2 Comparative C 100 100 100 604 Example 3

Referring to Table 2, it has been determined that the organic light-emitting devices of Examples 1 to 14 have improved driving voltage, quantum emission efficiency, and lifespan characteristics, as compared with those of the organic light-emitting devices of Comparative Examples 1 to 3.

Since the organometallic compounds have excellent electrical characteristics and thermal stability, organic light-emitting devices including such organometallic compounds may have excellent driving voltage, efficiency, power, color purity, and lifespan characteristics. Also, due to excellent phosphorescent luminescence characteristics, such organometallic compounds may provide a diagnostic composition having high diagnostic efficiency.

It should be understood that embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments.

While one or more embodiments have been described with reference to the FIGURES, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present description as defined by the following claims. 

What is claimed is:
 1. An organometallic compound represented by Formula 1:

wherein, in Formula 1, M is a first-row transition metal of the Periodic Table of Elements, a second-row transition metal of the Periodic Table of Elements, or a third-row transition metal of the Periodic Table of Elements, X₁ is N, X₂ to X₄ are each independently C or N, two bonds selected from a bond between X₁ and M, a bond between X₂ and M, a bond between X₃ and M, and a bond between X₄ and M are each a coordinate bond, and the others thereof are each a covalent bond, Y₁ to Y₆ are each independently C or N, Y₇ and Y₈ are each independently C, N, O, Si, or S, X₁ and Y₇, X₁ and Y₁, X₂ and Y₂, X₂ and Y₃, X₃ and Y₄, X₃ and Y₅, X₄ and Y₆, and X₄ and Y₈ are each linked via a chemical bond, CY₁ is a C₁-C₃₀ heterocyclic group, CY₂ to CY₄ are each independently a C₅-C₃₀ carbocyclic group or a C₁-C₃₀ heterocyclic group, T₁ to T₃ are each independently selected from *—N[(L₅)_(b5)-(R₅)]—*′, *—B(R₅)—*′, *—P(R₅)—*′, *—C(R₅)(R₆)—*′, *—Si(R₅)(R₆)—*′, *—Ge(R₅)(R₆)—*′, *—C(═O)—*′, *—S(═O)—*′, *—S(═O)₂—*′, *—C(R₅)═*′, *═C(R₅)—*′, *—C(R₅)═C(R₆)—*′, *—C(═S)—*′, and *—C≡C—*′, L₅ is selected from a single bond, a substituted or unsubstituted C₅-C₃₀ carbocyclic group, and a substituted or unsubstituted C₁-C₃₀ heterocyclic group, b5 is selected from 1 to 3, wherein, when b5 is two or more, two or more groups L₅ are identical to or different from each other, R₅ and R₆ are optionally linked via a first linking group to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, n1 to n3 are each independently 0, 1, 2, or 3, wherein, when n1 is zero, *-(T₁)_(n1)—*′ is a single bond, when n2 is zero, *-(T₂)_(n2)—*′ is a single bond, and when n3 is zero, *-(T₃)_(n3)-*′ is a single bond, provided that at least one of n1 to n3 is zero, R₇₁ in Formula 1 is a group represented by Formula 71, *-(L₇₁)_(b71)-(T₇₁)_(c71)  Formula 71 wherein, in Formula 71, L₇₁ is selected from: a C₂-C₆₀ alkylene group; and a C₂-C₆₀ alkylene group substituted with at least one selected from deuterium, a deuterated C₁-C₆₀ alkyl group, a C₃-C₁₀ cycloalkyl group, and a C₃-C₁₀ cycloalkenyl group, b71 is 0, 1, or 2, T₇₁ is selected from: a C₁-C₆₀ alkyl group; and a C₁-C₆₀ alkyl group substituted with at least one selected from deuterium, a deuterated C₁-C₆₀ alkyl group, a C₃-C₁₀ cycloalkyl group, and a C₃-C₁₀ cycloalkenyl group, c71 is an integer from 1 to 10, R₇₂ in Formula 1 is a group represented by Formula 72, *-(L₇₂)_(b72)-(T₇₂)_(c72),  Formula 72 wherein, in Formula 72, L₇₂ is selected from: a C₆-C₆₀ arylene group, a C₁-C₆₀ heteroarylene group, a divalent non-aromatic condensed polycyclic group, and a divalent non-aromatic condensed heteropolycyclic group; and a C₆-C₆₀ arylene group, a C₁-C₆₀ heteroarylene group, a divalent non-aromatic condensed polycyclic group, and a divalent non-aromatic condensed heteropolycyclic group, each substituted with at least one selected from deuterium, a C₁-C₆₀ alkyl group, a deuterated C₁-C₆₀ alkyl group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group, b72 is 0, 1, or 2, T₇₂ is selected from: a C₆-C₆₀ aryl group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group; and a C₆-C₆₀ aryl group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group, each substituted with at least one selected from deuterium, a C₁-C₆₀ alkyl group, a deuterated C₁-C₆₀ alkyl group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group, c72 is an integer from 1 to 10, wherein, in Formula 1, a71 and a72 are each independently an integer from 1 to 5, R₁ to R₆ are each independently selected from hydrogen, deuterium, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a substituted or unsubstituted C₇-C₆₀ arylalkyl group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstituted C₁-C₆₀ heteroaryloxy group, a substituted or unsubstituted C₁-C₆₀ heteroarylthio group, a substituted or unsubstituted C₂-C₆₀ heteroarylalkyl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉), a1 to a4 are each independently 0, 1, 2, 3, 4, or 5, Formula 1 does not include fluorine (—F), two of groups R₁ in the number of a1 are optionally linked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, two of groups R₂ in the number of a2 are optionally linked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, two of groups R₃ in the number of a3 are optionally linked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, two of groups R₄ in the number of a4 are optionally linked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, two or more neighboring groups selected from R₁ to R₄ are optionally linked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, one of R₅ and R₆ and one of R₁ to R₄ are optionally linked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, at least one substituent of the substituted C₅-C₃₀ carbocyclic group, the substituted C₁-C₃₀ heterocyclic group, the substituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀ alkenyl group, the substituted C₂-C₆₀ alkynyl group, the substituted C₁-C₆₀ alkoxy group, the substituted C₃-C₁₀ cycloalkyl group, the substituted C₁-C₁₀ heterocycloalkyl group, the substituted C₃-C₁₀ cycloalkenyl group, the substituted C₁-C₁₀ heterocycloalkenyl group, the substituted C₆-C₆₀ aryl group, the substituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀ arylthio group, the substituted C₇-C₆₀ arylalkyl group, the substituted C₁-C₆₀ heteroaryl group, the substituted C₁-C₆₀ heteroaryloxy group, the substituted C₁-C₆₀ heteroarylthio group, the substituted C₂-C₆₀ heteroarylalkyl group, the substituted monovalent non-aromatic condensed polycyclic group, and the substituted monovalent non-aromatic condensed heteropolycyclic group is selected from: deuterium, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy group; a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy group, each substituted with at least one selected from deuterium, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —N(Q₁₁)(Q₁₂), —Si(Q₁₃)(Q₁₄)(Q₁₅), —B(Q₁₆)(Q₁₇), and —P(═O)(Q₁₈)(Q₁₉); a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group; a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group, each substituted with at least one selected from deuterium, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅), —B(Q₂₆)(Q₂₇), and —P(═O)(Q₂₈)(Q₂₉); and —N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅), —B(Q₃₆)(Q₃₇), and —P(═O)(Q₃₈)(Q₃₉), and Q₁ to Q₉, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, and Q₃₁ to Q₃₉ are each independently selected from hydrogen, deuterium, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryl group substituted with at least one selected from a C₁-C₆₀ alkyl group, and a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group.
 2. The organometallic compound of claim 1, wherein M is Pt or Pd.
 3. The organometallic compound of claim 1, wherein CY₁ is selected from a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrrole group, a pyrazole group, an imidazole group, a triazole group, a tetrazole group, an oxazole group, an isoxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, a benzothiadiazole group, a 5,6,7,8-tetrahydroisoquinoline group, and a 5,6,7,8-tetrahydroquinoline group, and CY₂ to CY₄ are each independently selected from a benzene group, a naphthalene group, an anthracene group, a phenanthrene group, a triphenylene group, a pyrene group, a chrysene group, a cyclopentadiene group, a 1,2,3,4-tetrahydronaphthalene group, a pyrrole group, a thiophene group, a furan group, an indole group, a benzoborol group, a benzophosphole group, an indene group, a benzosilole group, a benzogermole group, a benzothiophene group, a benzoselenophene group, a benzofuran group, a carbazole group, a dibenzoborole group, a dibenzophosphole group, a fluorene group, a dibenzosilole group, a dibenzogermole group, a dibenzothiophene group, a dibenzoselenophene group, a dibenzofuran group, a dibenzothiophene 5-oxide group, a 9H-fluorene-9-on group, a dibenzothiophene 5,5-dioxide group, an azacarbazole group, an azadibenzoborole group, an azadibenzophosphole group, an azafluorene group, an azadibenzosilole group, an azadibenzogermole group, an azadibenzothiophene group, an azadibenzoselenophene group, an azadibenzofuran group, an azadibenzothiophene 5-oxide group, an aza-9H-fluorene-9-on group, an azadibenzothiophene 5,5-dioxide group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrazole group, an imidazole group, a triazole group, a tetrazole group, an oxazole group, an isoxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, a benzothiadiazole group, a 5,6,7,8-tetrahydroisoquinoline group, and a 5,6,7,8-tetrahydroquinoline group.
 4. The organometallic compound of claim 1, wherein, in Formula 1, a moiety represented by

and a moiety represented by

are identical to each other, and a moiety represented by

and a moiety represented by

are identical to each other.
 5. The organometallic compound of claim 1, wherein T₁ to T₃ are each independently selected from *—N[(L₅)_(b5)-(R₅)]—*′, *—C(R₅)(R₆)—*′, *—Si(R₅)(R₆)—*′, *—S—*′, and *—O—*′, and the sum of n1, n2, and n3 is
 1. 6. The organometallic compound of claim 1, wherein L₇₁ is selected from: a C₂-C₁₀ alkylene group; and a C₂-C₁₀ alkylene group substituted with at least one selected from deuterium, a deuterated C₁-C₂₀ alkyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an adamantanyl group, a norbonanyl group, a norbonenyl group, a cyclopentenyl group, a cyclohexenyl group, and a cycloheptenyl group, b71 is 0 or 1, T₇₁ is selected from: a C₁-C₁₀ alkyl group; and a C₁-C₁₀ alkyl group substituted with at least one selected from deuterium, a deuterated C₁-C₂₀ alkyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an adamantanyl group, a norbonanyl group, a norbonenyl group, a cyclopentenyl group, a cyclohexenyl group, and a cycloheptenyl group, and c71 is 1 or
 2. 7. The organometallic compound of claim 1, wherein L₇₂ is selected from: a phenylene group, a naphthylene group, a pyridinylene group, a pyrimidinylene group, a triazinylene group, a quinolinylene group, an isoquinolinylene group, a quinoxalinylene group, a quinazolinylene group, a fluorenylene group, a carbazolylene group, a dibenzofuranylene group, and a dibenzothiophenylene group; and a phenylene group, a naphthylene group, a pyridinylene group, a pyrimidinylene group, a triazinylene group, a quinolinylene group, an isoquinolinylene group, a quinoxalinylene group, a quinazolinylene group, a fluorenylene group, a carbazolylene group, a dibenzofuranylene group, and a dibenzothiophenylene group, each substituted with at least one selected from deuterium, a C₁-C₂₀ alkyl group, a deuterated C₁-C₂₀ alkyl group, a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, b72 is 0 or 1, T₇₂ is selected from: a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group; and a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, each substituted with at least one selected from deuterium, a C₁-C₂₀ alkyl group, a deuterated C₁-C₂₀ alkyl group, a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, and c72 is 1 or
 2. 8. The organometallic compound of claim 1, wherein R₁ to R₆ are each independently selected from: hydrogen, deuterium, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, C₁-C₂₀ alkyl group, and a C₁-C₂₀ alkoxy group; a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group, each substituted with at least one selected from deuterium, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an adamantanyl group, a norbornanyl group, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, a phenyl group, a naphthyl group, a pyridinyl group, and a pyrimidinyl group; a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an adamantanyl group, a norbornanyl group, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group; a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an adamantanyl group, a norbornanyl group, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group, each substituted with at least one selected from deuterium, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an adamantanyl group, a norbornanyl group, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, —N(Q₃₁)(Q₃₂), and —Si(Q₃₃)(Q₃₄)(Q₃₅); and —N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉), and Q₁ to Q₉ and Q₃₁ to Q₃₅ are each independently selected from: CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃, —CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂; an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a phenyl group, and a naphthyl group; and an n-propyl group, an iso-propyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a phenyl group, and a naphthyl group, each substituted with at least one selected from deuterium, a C₁-C₁₀ alkyl group, and a phenyl group.
 9. The organometallic compound of claim 1, wherein R₁ to R₆ are each independently selected from hydrogen, deuterium, a cyano group, a nitro group, —CH₃, —CD₃, —CD₂H, —CDH₂, —OCH₃, groups represented by Formulae 9-1 to 9-19, groups represented by Formulae 10-1 to 10-168, —N(Q₁)(Q₂), and —Si(Q₃)(Q₄)(Q₅), R₇₁ is selected from —CH₃, —CD₃, —CD₂H, —CDH₂, groups represented by Formulae 9-1 to 9-19, and groups represented by Formulae 10-5 to 10-8, 10-11, and 10-12, and R₇₂ is selected from groups represented by Formulae 10-13 to 10-152 and 10-159 to 10-168:

wherein, in Formulae 9-1 to 9-19 and 10-1 to 10-168, * indicates a binding site to a neighboring atom, “Ph” indicates a phenyl group, “Cz” indicates a carbazolyl group, and “TMS” indicates a trimethylsilyl group.
 10. The organometallic compound of claim 1, wherein a moiety represented by

in Formula 1 is selected from groups represented by Formulae CY1-1 to CY1-6:

wherein, in Formulae CY1-1 to CY1-6, X₁, R₇₁, R₇₂, and R₁ are each independently the same as described in claim 1, c2 is an integer from 0 to 2, and * and *′ each indicate a binding site to a neighboring atom.
 11. The organometallic compound of claim 1, wherein, a moiety represented by

Formula 1 is selected from groups represented by Formulae CY2-1 to CY2-25:

wherein, in Formulae CY2-1 to CY2-25, X₂ and R₂ are each independently the same as described in claim 1, X₂₁ is O, S, N(R₂₁), or C(R₂₁)(R₂₂), R₂₁ to R₂₈ are each independently the same as described in connection with R₂ in claim 1, c5 is an integer from 0 to 5, c4 is an integer from 0 to 4, c3 is an integer from 0 to 3, c2 is an integer from 0 to 2, and *, *′, and *″ each indicate a binding site to a neighboring atom.
 12. The organometallic compound of claim 1, wherein a moiety represented by

in Formula 1 is selected from groups represented by Formulae CY3-1 to CY3-25:

wherein, in Formulae CY3-1 to CY3-25, X₃ and R₃ are each independently the same as described in claim 1, X₃₁ is O, S, N(R₃₁), or C(R₃₁)(R₃₂), R₃₁ to R₃₈ are each independently the same as described in connection with R₃ in claim 1, c5 is an integer from 0 to 5, c4 is an integer from 0 to 4, c3 is an integer from 0 to 3, c2 is an integer from 0 to 2, and *, *′, and *″ each indicate a binding site to a neighboring atom.
 13. The organometallic compound of claim 1, wherein a moiety represented by

in Formula 1 is selected from groups represented by Formulae CY4-1 to CY4-35:

wherein, in Formulae CY4-1 to CY4-35, X₄ and R₄ are each independently the same as described in claim 1, X₄₁ is O, S, N(R₄₁), or C(R₄₁)(R₄₂), R_(71a) is the same as described in connection with R₇₁ in claim 1, R_(72a) is the same as described in connection with R₇₂ in claim 1, R₄₁ to R₄₈ are each independently the same as described in connection with R₄ in claim 1, c6 is an integer from 0 to 6, c5 is an integer from 0 to 5, c4 is an integer from 0 to 4, c3 is an integer from 0 to 3, c2 is an integer from 0 to 2, and * and *′ each indicate a binding site to a neighboring atom.
 14. The organometallic compound of claim 1, wherein a moiety represented by

in Formula 1 is selected from groups represented by Formulae CY1(1) and CY1(2), a moiety represented by

in Formula 1 is selected from groups represented by Formulae CY2(1) to CY2(4), a moiety represented by

in Formula 1 is selected from groups represented by Formulae CY3(1) to CY3(4), and a moiety represented by

in Formula 1 is selected from groups represented by Formulae CY4(1) to CY4(19):

wherein, in Formulae CY1(1), CY1(2), CY2(1) to CY2(4), CY3(1) to CY3(4), and CY4(1) to CY4(19), X₁, R₁, R₇₁, R₇₂, X₂, R₂, X₃, R₃, X₄, and R₄ are each independently the same as described in claim 1, X₄₁ is O, S, N(R₄₁), or C(R₄₁)(R₄₂), R_(4a), R_(4b), R₄₁, and R₄₂ are each independently the same as described in connection with R₄ in claim 1, R_(71a) is the same as described in connection with R₇₁ in claim 1, R_(72a) is the same as described in connection with R₇₂ in claim 1, and *, *′, and *″ each indicate a binding site to a neighboring atom.
 15. An organometallic compound represented by Formula 1(1):

wherein, in Formula 1(1), M is a first-row transition metal of the Periodic Table of Elements, a second-row transition metal of the Periodic Table of Elements, or a third-row transition metal of the Periodic Table of Elements, X₁ is N, X₂ to X₄ are each independently C or N, two bonds selected from a bond between X₁ and M, a bond between X₂ and M, a bond between X₃ and M, and a bond between X₄ and M are each a coordinate bond, and the others thereof are each a covalent bond, Y₁ to Y₆ are each independently C or N, Y₇ and Y₈ are each independently C, N, O, Si, or S, X₁ and Y₇, X₁ and Y₁, X₂ and Y₂, X₂ and Y₃, X₃ and Y₄, X₃ and Y₅, X₄ and Y₆, and X₄ and Y₈ are each linked via a chemical bond, CY₁ is a C₁-C₃₀ heterocyclic group, CY₂ to CY₄ are each independently a C₅-C₃₀ carbocyclic group or a C₁-C₃₀ heterocyclic group, T₂ and T₃ are each independently selected from *—N[(L₅)_(b5)-(R₅)]—*′, *—B(R₅)—*′, *—P(R₅)—*′, *—C(R₅)(R₆)—*′, *—Si(R₅)(R₆)—*′, *—Ge(R₅)(R₆)—*′, *—S—*′, *—O—*′, *—C(═O)—*′, *—S(═O)—*′, *—S(═O)₂—*′, *—C(R₅)═*′, *═C(R₅)—*′, *—C(R₅)═C(R₆)—*′, *—C(═S)—*′, and *—C≡C—*′, L₅ is selected from a single bond, a substituted or unsubstituted C₅-C₃₀ carbocyclic group, and a substituted or unsubstituted C₁-C₃₀ heterocyclic group, b5 is selected from 1 to 3, wherein, when b5 is two or more, two or more groups L₅ are identical to or different from each other, R₅ and R₆ are optionally linked via a first linking group to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, n2 and n3 are each independently 0, 1, 2, or 3, wherein, when n2 is zero, *-(T₂)_(n2)—*′ is a single bond, and when n3 is zero, *-(T₃)_(n3)—*′ is a single bond, R₇₁ in Formula 1(1) is a group represented by Formula 71, *-(L₇₁)_(b71)-(T₇₁)_(c71)  Formula 71 wherein, in Formula 71, L₇₁ is selected from: a C₂-C₆₀ alkylene group; and a C₂-C₆₀ alkylene group substituted with at least one selected from deuterium, a deuterated C₁-C₆₀ alkyl group, a C₃-C₁₀ cycloalkyl group, and a C₃-C₁₀ cycloalkenyl group, b71 is 0, 1, or 2, T₇₁ is selected from: a C₁-C₆₀ alkyl group; and a C₁-C₆₀ alkyl group substituted with at least one selected from deuterium, a deuterated C₁-C₆₀ alkyl group, a C₃-C₁₀ cycloalkyl group, and a C₃-C₁₀ cycloalkenyl group, c71 is an integer from 1 to 10, R₇₂ in Formula 1(1) is a group represented by Formula 72, *-(L₇₂)_(b72)-(T₇₂)_(c72),  Formula 72 wherein, in Formula 72, L₇₂ is selected from: a C₆-C₆₀ arylene group, a C₁-C₆₀ heteroarylene group, a divalent non-aromatic condensed polycyclic group, and a divalent non-aromatic condensed heteropolycyclic group; and a C₆-C₆₀ arylene group, a C₁-C₆₀ heteroarylene group, a divalent non-aromatic condensed polycyclic group, and a divalent non-aromatic condensed heteropolycyclic group, each substituted with at least one selected from deuterium, a C₁-C₆₀ alkyl group, a deuterated C₁-C₆₀ alkyl group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group, b72 is 0, 1, or 2, T₇₂ is selected from: a C₆-C₆₀ aryl group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group; and a C₆-C₆₀ aryl group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group, each substituted with at least one selected from deuterium, a C₁-C₆₀ alkyl group, a deuterated C₁-C₆₀ alkyl group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group, c72 is an integer from 1 to 10, wherein, in Formula 1(1), a71 and a72 are each independently an integer from 1 to 5, R₁ to R₆ are each independently selected from hydrogen, deuterium, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a substituted or unsubstituted C₇-C₆₀ arylalkyl group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstituted C₁-C₆₀ heteroaryloxy group, a substituted or unsubstituted C₁-C₆₀ heteroarylthio group, a substituted or unsubstituted C₂-C₆₀ heteroarylalkyl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉), a1 to a4 are each independently 0, 1, 2, 3, 4, or 5, Formula 1(1) does not include flourine (—F), CY₅ and CY₆ are each independently be a C₅-C₃₀ carbocyclic group or a C₁-C₃₀ heterocyclic group, R₅₁ and R₆₁ are each independently the same as described in connection with R₁ described above, a51 and a61 are each independently be 0, 1, 2, or 3, T₄ is C, Si, or Ge, T₅ is selected from a single bond, *—N[(L₇)_(b7)-(R₇)]—*′, *—C(R₇)(R₈)—*′, *—Si(R₇)(R₈)—*′, *—Ge(R₇)(R₈)—*′, *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′, *—S(═O)—*′, *—S(═O)₂—*′, *—C(R₇)═C(R₈)—*′, *—C(═S)—*′, and *—C≡C—*′, L₇ and b7 are each independently the same as described in connection with L₅ and b5 described above, R₇ and R₅ are each independently the same as described in connection with R₅, and * and *′ each indicate a binding site to a neighboring atom, two of groups R₁ in the number of a1 are optionally linked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, two of groups R₂ in the number of a2 are optionally linked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, two of groups R₃ in the number of a3 may optionally be linked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, two of groups R₄ in the number of a4 may optionally be linked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, two or more neighboring groups selected from R₁ to R₄ may optionally be linked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, one of R₅ and R₆ and one of R₁ to R₄ may optionally be linked to form a substituted or unsubstituted C₅-C₃₀ carbocyclic group or a substituted or unsubstituted C₁-C₃₀ heterocyclic group, at least one substituent of the substituted C₅-C₃₀ carbocyclic group, the substituted C₁-C₃₀ heterocyclic group, the substituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀ alkenyl group, the substituted C₂-C₆₀ alkynyl group, the substituted C₁-C₆₀ alkoxy group, the substituted C₃-C₁₀ cycloalkyl group, the substituted C₁-C₁₀ heterocycloalkyl group, the substituted C₃-C₁₀ cycloalkenyl group, the substituted C₁-C₁₀ heterocycloalkenyl group, the substituted C₆-C₆₀ aryl group, the substituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀ arylthio group, the substituted C₇-C₆₀ arylalkyl group, the substituted C₁-C₆₀ heteroaryl group, the substituted C₁-C₆₀ heteroaryloxy group, the substituted C₁-C₆₀ heteroarylthio group, the substituted C₂-C₆₀ heteroarylalkyl group, the substituted monovalent non-aromatic condensed polycyclic group, and the substituted monovalent non-aromatic condensed heteropolycyclic group may be selected from: deuterium, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy group; a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy group, each substituted with at least one selected from deuterium, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —N(Q₁₁)(Q₁₂), —Si(Q₁₃)(Q₁₄)(Q₁₅), —B(Q₁₆)(Q₁₇), and —P(═O)(Q₁₈)(Q₁₉); a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group; a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group, each substituted with at least one selected from deuterium, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅), —B(Q₂₆)(Q₂₇), and —P(═O)(Q₂₈)(Q₂₉); and —N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅), —B(Q₃₆)(Q₃₇), and —P(═O)(Q₃₈)(Q₃₉), and Q₁ to Q₉, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, and Q₃₁ to Q₃₉ are each independently selected from hydrogen, deuterium, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryl group substituted with at least one selected from a C₁-C₆₀ alkyl group and a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group.
 16. The organometallic compound of claim 1, wherein the organometallic compound is selected from Compounds 1 to 201:


17. An organic light-emitting device comprising: a first electrode; a second electrode; and an organic layer that is disposed between the first electrode and the second electrode, wherein the organic layer comprises an emission layer and at least one of the organometallic compound of claim
 1. 18. The organic light-emitting device of claim 17, wherein the first electrode is an anode, the second electrode is a cathode, the organic layer further comprises a hole transport region disposed between the first electrode and the emission layer and an electron transport region disposed between the emission layer and the second electrode, wherein the hole transport region comprises a hole injection layer, a hole transport layer, an electron blocking layer, or any combination thereof, and wherein the electron transport region comprises a hole blocking layer, an electron transport layer, an electron injection layer, or any combination thereof.
 19. The organic light-emitting device of claim 17, wherein the emission layer comprises the organometallic compound.
 20. The organic light-emitting device of claim 19, wherein the emission layer further comprises a host, and an amount of the host in the emission layer is larger than an amount of the organometallic compound in the emission layer.
 21. A diagnostic composition comprising at least one of the organometallic compound of claim
 1. 